brain-teaser: that balance between flash + ambient light
With everyone’s response to the two recent articles,
- bouncing on-camera flash in manual mode, and
- TTL bounce flash at wedding receptions,
I thought these two images made for an interesting comparison and discussion.
Both were taken with TTL bounce flash, and the same camera settings. (1/160 @ f/4.5 @ 1600 ISO). Both are JPGs generated from the edited RAW files. Yet, they look very different in how the flash and ambient light appear to be balanced.
As a brain-teaser for everyone … why would there be such a difference?
Let’s hear some discussion and ideas. (A hint: the answer isn’t complicated.)
Entries are now closed ( Nov 26, 2012)
To keep it interesting, I’m offering an incentive to participate in the challenge: An individual tutoring session (1 hr) via Skype each for two people who will be picked from the replies here.
The two entries that will be picked:
– One person from those that figure it out correctly;
– along with one other person who responds to this post, whether their reply is correct or not.
(The only restriction is those who win the tutoring session, need to be fluent in English.)
We’ll let this run until Monday, Nov 26th.
Edited to add:
After reading the first 50 entries, I want to nudge the discussion towards the light:
- I mentioned at the start that I used the same camera settings. I didn’t change the camera settings, nor the exposure mode of the camera.- my flash was bounced in exactly the same way for both images. I didn’t change the angle. I didn’t change my light modifier.
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I would guess that the difference is due to the first shot using bounce flash and the second shot being direct flash.
Comment by Simon — November 20, 2012 @ 4:07 am
Perhaps the flash is bounced in a manner that allows it to reach more of the room which lightens that area that is pretty dark in the first photo.
Comment by Mylan — November 20, 2012 @ 4:17 am
First one was bounced further awat fron the wall than the second darker one. Inverse square law.
Comment by Mirza — November 20, 2012 @ 4:35 am
In the second image I’d say that the flash is bounced backwards over the left shoulder and is flagged to reduce light spill.
In the first image, I’d say the flash is bounced off the ceiling (more to the right I think) and is un-flagged.
Comment by Lyn Rees — November 20, 2012 @ 4:51 am
It is that you bounced your flash in the last photo to the ceiling and in the first photo to the room behind you (in order to create a larger light source?)
Comment by GP — November 20, 2012 @ 4:52 am
Both are bounce. The first with exposure corrections on both DLSR and flash. Like +1 on DLSR and -1 on flash.
Comment by Jan — November 20, 2012 @ 4:56 am
Looks like its the distance between yourself and the bounce surface. The first image the ladies and the back walls are both further from the bounce wall. It looks like you stepped back closer to the bounce wall and got more light back to the ladies and less light into the back of the room.
Comment by Ricardo Mendoza — November 20, 2012 @ 4:56 am
Hi,
My guess is the following: first image => the flash is pointed (at least partly) at the people in front of the camera and is diffused using an omnibounce and the second shot is done using the BFT to flag the flashgun which is bounced to the wall(s) on the right and the back of the camera…
Hope I win a tutoring session with the “Master of flash” :-)
Frédéric
Comment by Frederic Blu — November 20, 2012 @ 5:06 am
Hi,
I would suspect that your BFT was not in place in the first pic.
Cathal
Comment by Cathal — November 20, 2012 @ 5:11 am
As someone who has never bounced a flash and doesn’t own a speedlight (looking to purchase one as my next kit addition) I would say that the main difference is because the 1st photo has actually more ambient light in it.
Looks like the group of people is closer to both the ceiling and side wall lights. The angle of the 1st photo appears to include more of the light sources.
Just a guess!
Comment by Mark — November 20, 2012 @ 5:22 am
Evaluative vs. spot metering?
Comment by Corinne — November 20, 2012 @ 5:46 am
inverse square law……..to quote YOU:”In a real shooting situation, we might not get as technical as that. We just need an innate understanding of what is going on. The further our subject+background moves from the light source, the brighter our background will appear, relative to when our subject+background is much closer to the light source.
Comment by mike — November 20, 2012 @ 5:48 am
both shots also bounced flash backward on camera right. First shot, the distant of the background is far so appear to be darker. Second shot, camera move to 7-8 o’clock position of the subject, so that the side wall distant is closer and appear to be brighter due to inverse square law.
Comment by David — November 20, 2012 @ 5:59 am
Here’s my attempt… Since on-camera TTL flash was used, this means that the position of the light source (flash) is the same as the camera.
First image: The lens was at the telephoto end, which means that camera is further away from the subjects, and so is the light source.
Second image: The lens was at the wide angle end, which means that camera is nearer to the subjects, and so is the light source.
Because of the inverse square law, the light fall-off is more dramatic in the second image.
Comment by Andy Lim — November 20, 2012 @ 6:21 am
Hi, I guess that for the first image you bounced the light forward and up on TTL and the second was bounced directly behind you with the flash on manual.
Thanks for providing the stream of technical advice.
Michael
Comment by Michael Mariner — November 20, 2012 @ 6:40 am
I think the first (better) image was shot with a longer focal distance then the 2nd image. Therefore the lightsource was further away and the inverse law did the job.
Comment by Alwin — November 20, 2012 @ 6:49 am
Inverse square law.
In the first photo, the object that you bounced the flash off of was much further away from the subject, so there was much less light falloff between the subject and the background. Looks like maybe you bounced into the far corner of the room.
In the second photo, the object you bounced off of was much closer to the subject, so there was much more light falloff between the subject and the background. It looks like you bounced off of a wall directly behind you.
This is just the same as shooting with a soft box and the affect it would have on the background if it was close or far from the subject.
Comment by Steve Holmes — November 20, 2012 @ 7:06 am
First one was shot with a lower shutter speed (dragging the shutter) and perhaps a higher iso…
Comment by Erwin Beckers — November 20, 2012 @ 7:28 am
I would say you changed the zoom on the flash – wide on first and tele on second
Comment by Malc — November 20, 2012 @ 7:53 am
I’m going to go with the first one you bounced the flash behind you, (into the room), and the second towards the subjects.
This is a great visual, thank you so much for sharing!! I’ve learnt so much from reading your posts.
Comment by Annette — November 20, 2012 @ 7:55 am
In the second image, you turned to your left, away from the side wall, effectively making it farther from the camera.
Comment by Buz — November 20, 2012 @ 8:08 am
I think, the group was moving towards you and you were compensating this with a zoom lens. As usual, you bounced the flash behind you.
In the first photo the group was further away from you, in the second they were closer and you zoomed to a wider angel.
Because of the inverse square law, in the second image you had a stronger light fall-off.
BTW: Thanks for this wonderful blog! Before reading you I was an ‘available light shooter’. Now I love using my speedlight!
Comment by Carsten — November 20, 2012 @ 8:46 am
In the first shot, you were closer to the center of the room, so the distance the light had to travel from the flash to the wall and then back to the group was much further. The flash output would also have been much higher to compensate and even things out between shots. As light falls off slower the farther it gets from the source (Inverse square law), the subjects and room would be much more evenly lit.
Comment by Greg Benedict — November 20, 2012 @ 8:51 am
In the upper photo, the flash was bounced off the wall behind you, or another surface that was relatively far from the subjects.
In the lower photo, the flash was bounced off the ceiling or a surface relatively closer to the subjects.
The inverse-square law comes into play to govern how evenly the entire room is lit by the combination of flash and ambient.
Comment by Chris Kagy — November 20, 2012 @ 9:03 am
It looks like you’ve moved position in the room & are bouncing the flash from a wall/ceiling further away than in the first shot, hence the light fall off.
Comment by paul mcgreevy — November 20, 2012 @ 9:15 am
Both are shot with same camera settings, both used TTL bounce flash -> in the first one you and the subjects were farther away from the wall than in the second. Since the flash has farther to travel in the first, the ambient is more obvious. In the second (closer) shot, the camera calculated less power needed to light subject at focus point.
Comment by Jim — November 20, 2012 @ 9:24 am
the foregone bounced off the ceiling behind you. The second one bounced off a wall behind you which was a little farther. Inverse square law.
Comment by venkat — November 20, 2012 @ 9:28 am
It appears to me that it got darker outside (looks like there’s natural light coming from camera left and from the opposite end of the room), and therefore there’s less ambient light.
Comment by Josh — November 20, 2012 @ 9:36 am
I’m going for the angle of the bounce flash being the difference between the two images. In the top one the flash is bounced behind and parallel to the floor, thus lighting the length of the room. In the bottom image the flash is again bounced behind, but the flash is angled towards the ceiling.
Comment by Andy Moss — November 20, 2012 @ 9:38 am
I notice a colour cast on the images – top one looks warmer, so could you be bouncing off different surfaces and so the power of the flash was more effective in top pic? In reality, this is probably an AUTO White balance issue, but despite your suggestion the answer is simple, I’m stumped!Damn you for making us wait until Monday!
Comment by stu — November 20, 2012 @ 9:45 am
In both pictures the flash is bounced back over your right shoulder (and also tilted upwards) but on the second picture you flaged the right side of the flash with the black foamie thing. Just my guess
Comment by Alex — November 20, 2012 @ 9:48 am
Thinking that the second pic is spot-metered on the subjects’ skin, and bounced from perhaps the ceiling (judging the bust area shadows, and light patch on the ceiling); whereas the first pic is metered on a darker part of the room somewhere in the background (perhaps matrix) and bounced From somewhere that gives a large even light source to the whole room – perhaps wall behind camera.
Comment by Dr Sooll — November 20, 2012 @ 9:57 am
The first image was bounce over his shoulder and the second image was bounced off the wall to his right.
Comment by Ted — November 20, 2012 @ 10:00 am
I think the answer is simply that your angle to the subjects changed (as evidenced by the chandeliers). In the first one, the bounced light was able to bounce off the side wall and add more light to the background.
Comment by Andrea Javarauckas — November 20, 2012 @ 10:03 am
I think the difference is in the direction of the bounced light and the distance to the walls behind the subjects. The second photo lost a stop or more due to the inverse square law thing.
The ambient appears to be balanced in the first photo because the bounced flash is hitting the walls behind the subjects at an angle which illuminates the the wall and the walls are closer to the camera.
In the second photo, the the angle between the bounced light and the walls are too shallow and the walls are also further away, so not enough of the rebounced flash from the walls behind the subjects didn’t make it back to the sensor.
Comment by ysphoto — November 20, 2012 @ 10:09 am
My guess –
Shot one: Flash bounced into wall behind. Shot two, flash bounced off ceiling.
Comment by Ben Jamieson — November 20, 2012 @ 10:30 am
Both are bounced, the first bounced forward off the ceiling the second on wall behind.
Comment by Michael Mariner — November 20, 2012 @ 10:42 am
#1 was probably bounced from a wall behind you.
#2 due to the strong light fall off under the girls chins , i would say bounced from the ceiling.
Comment by Francisco Onofre — November 20, 2012 @ 10:46 am
In the first image, the bounce surface is farther away from the women than in the second image. This illustrates the inverse-square law you often write about.
Comment by Jeff Mason — November 20, 2012 @ 11:03 am
My guess is that the darker image had you standing fairly close to the wall behind you making the distance from the wall you bounced off very close to the subjects and inviting a faster light fall off. In the brighter photo you changed your angle to put more distance between you and the the back corner you bounced off of therefore making better use of the inverse square law by making the background relatively closer in relation to the bounced surface.
Comment by Gene — November 20, 2012 @ 11:04 am
I would wager that for the second shot,the photographer positioned himself so that there was a wall or something else behind his subject, as well as a wall being behind him. That way he could bounce flash off the wall either behind or to his side, which would then illuminate the guests with nice soft light. Additionally, the wall behind the ladies, being not as far away as the one in the first example, would be able to pick up just enough of that light to not be the black hole the first example background was.
Comment by Gregory Hitchcock — November 20, 2012 @ 11:07 am
The flash wasn’t able to recycle fast enough
Comment by John — November 20, 2012 @ 11:07 am
It is either that the bounce surface is closer in the second image, or more likely that the angle of the first image shows more of the wall on the right side of the room, which is illuminated by the lights on said wall. The reason, I think the latter is more likely is because the flash does not appear to be reaching the back of the room in the first image. The fall off on the ladies behind the “catcher” is pretty quick on both of them. Further, the mirrors on the first image are in the shot reflecting the light from outside on the left. The final reason there might be a difference is that the first image is zoomed more. It might zoom your flash head and possibly change the character of the light bouncing against the wall. Light’s tricky.
Comment by Sam — November 20, 2012 @ 11:27 am
In the second image, someone blocked Neil’s flash by walking in between the flash and the rest of the room. This person effectively became the “light source” instead of the wall.
Comment by Justin — November 20, 2012 @ 11:29 am
I blame the mirrors throughout the room. Bouncing flash in a mirrored room is a giant PITA.
Comment by Chris — November 20, 2012 @ 11:35 am
Both are flash bounce, but the direction of the flash head is different in both.
1st – bounced on wall(s) behind/to the right … did you hit a mirror too? I see hard flash shadow on the nearest exit sign
2nd – bounced on ceiling and to the left (telltale spill on ceiling / upper left of photo)
Cheers!
Comment by Graham — November 20, 2012 @ 11:37 am
Photo 1 shot in AV or TV mode to balance flash with the ambient light.
Photo 2 shot in Program (auto) mode.
Comment by Kevin — November 20, 2012 @ 11:41 am
Hi Neil,
You have changed your flash to slow sync.
Darren
Comment by DARREN — November 20, 2012 @ 11:48 am
1st image flash was aimed behind and up a bit. 2nd photo the flash was aimed right
Comment by Mike Whealan — November 20, 2012 @ 11:50 am
Comment by Neil vN — November 20, 2012 @ 12:11 pm
Hi, the answer is really easy.
There are many more smiling women on first photo, which brighten the image! That’s the point :)
Comment by TomB — November 20, 2012 @ 12:39 pm
I’m thinking that one was taken closer to the subjact at a wider focal length and the othe further back at a longer focal length.
Comment by Joel Callaway — November 20, 2012 @ 12:40 pm
I think the direction that you pointed the flash was different in each.(shadows on faces) Also I think in one you use the BFT and the other you didn’t.
Comment by George Warren — November 20, 2012 @ 12:41 pm
The first one you held your hand up and bounced flash off of it.
Comment by Mandy — November 20, 2012 @ 12:42 pm
metering mode – second one was spot, first was matrix or center-weighted
Comment by April — November 20, 2012 @ 12:43 pm
The first one is shot at an angle to a nearby wall (which gets fill from the flash), the second is shot down the length of the hall (too far to fill from the flash). Plus the first one has some wall-mounted lights in it, which aids the perception of more ambient lighting.
Comment by Rob — November 20, 2012 @ 12:44 pm
oh wait i didn’t read the other comments — one was bounced off the ceiling one was bounced from the side?
Comment by April — November 20, 2012 @ 12:44 pm
If the flash angle was the same and the camera settings were the same, the only way to increase or decrease the amount of light so dramatically without moving speed light angle would be to move the black modifier you use, creating more of a localized bounce for the darker image…less spill.
I’m using one of these for my next wedding. The IQ/light quality you get is amazing.
Comment by Steven Mackie — November 20, 2012 @ 12:46 pm
Looks like the large mirror in image one helps lighten the image.
Comment by Will King — November 20, 2012 @ 12:47 pm
Looks like Inverse Square Law in play? In the first pic, the flash was placed further from the subject than in the second pic. In the second pic, the flash might have been placed very close to the subjects which made the light fall off.
Thanks
Satish
Comment by Satish Inuganti — November 20, 2012 @ 12:49 pm
The 1st image appears to be zoomed in and the 2nd image zoomed out but closer to subjects (more cieling and lower body shown), which might have effected the appearance of flash to ambient mix in an image.
Comment by Ken — November 20, 2012 @ 12:50 pm
In the first photo, you bounced the flash off the wall right behind you. This gives a very soft light (light wraps around very nicely) and the light falls off evenly to the back of the wall (Inverse Square Law). In the second photo, you used direct flash. I see hard light and shadow under the chin of the ladies. It’s also possible that you must have manually zoomed the flash in/out.
Comment by Marino Aloysius — November 20, 2012 @ 12:50 pm
I would say it’s the difference in focal length when two photos were taken.
Comment by Alberto — November 20, 2012 @ 12:51 pm
or you had a second light set up and it didn’t fire.
Comment by Mandy — November 20, 2012 @ 12:51 pm
Since your subjects are properly exposed in both images, I’m going to assume that your flash output was the same. I think it’s the background that makes the biggest change in the photos. For the first one, you’re BG is the side wall which is much closer (and thus brighter), and the second you’re shooting down the long length of the room, where you’re seeing the back wall which is too far for your flash to reach effectively.
Comment by Daniel Sullivan — November 20, 2012 @ 12:53 pm
my guess is that your flash unit wasn’t fully charged between these shots as it was propably putting out quite some power in “TTL bounce mode” ;-), brgds Michael
Comment by Michael Rieder — November 20, 2012 @ 12:54 pm
My guess is that the lights in the room were turned up more in the first (top) photo than in the second (bottom) one…?! Thus, the ambient light was different.
Comment by Lee Ann Baker — November 20, 2012 @ 12:55 pm
I haven’t checked the responses above, but my guess is that the difference is where you were standing thus what direction/distance the flash was bounced.
Comment by Mercedes — November 20, 2012 @ 12:55 pm
I agree with Malc (#19 – zoom on flash was changed
Comment by Angela R — November 20, 2012 @ 12:57 pm
I’m going to guess that you metered from a different area, or changed the flash exposure compensation.
Comment by courtney — November 20, 2012 @ 12:57 pm
I think that somebody appeared between flash and your bounce wall and your light source changed this way. TTL did his job, so first plane is corectly luminated, but the rest of the area didn’t.
Best regards, Tad
Comment by Tad — November 20, 2012 @ 12:57 pm
Additonal ambient light. Looks like more light coming through from a corridor next to glass windows? Someone turned a light on?
Comment by Scott — November 20, 2012 @ 12:57 pm
You used TTL-BL to have the camera balance the background exposure. In the second shot, that chandelier is pretty prominent in the frame. If we want more of an even ambient light in the background, we have to avoid bright objects being in the background of the frame.
Comment by Robert — November 20, 2012 @ 12:59 pm
You exposed for the background and ttl filled the foreground
Comment by Blair — November 20, 2012 @ 12:59 pm
The way the shadows in the dresses appear to be filled in the second shot, I’m probably inclined to suggest that the dimmers on the chandeliers were turned up. If your flash light direction was consistent between the two shots, I would expect the dress texture to remain the same. Clearly *something* is filling those shadows. Because the back of the room appears to be well illuminated compared to the first shot and I would guess that your flash would not be powerful enough to reach that far without overexposing your subject, yes, my guess is, the ambient light changed between the two shots.
Comment by Rob Mirage — November 20, 2012 @ 1:00 pm
If the settings on the camera are the same in both images and the flash was set the same and pointed in the same direction I would have to say the first image you used FEL button and metered the face and the second image you didn’t.
Comment by John — November 20, 2012 @ 1:01 pm
The top photo was shot with a longer focal length, even though the subjects appear the same size in the frame for both shots. So the camera to subject distance changed between those two frames. Neil must have stepped back and zoomed in a bit. The longer distance of the top frame allowed the flash to have a greater exposure coverage (less fall off). In the bottom frame, the light falls off quicker due to closer distance.
Comment by Ryan Tolbert — November 20, 2012 @ 1:05 pm
I tried to post this once so I will keep it short, FEL button on the first image metering off the face and not on the second?
Comment by John — November 20, 2012 @ 1:05 pm
First image, the flash was bounced from behind you. Second image, the flash was bounced to your right.
Comment by Ed — November 20, 2012 @ 1:06 pm
The room lights were turned up.
(makes focusing easier too – especially on my oldest camera).
Comment by Frank Courtney — November 20, 2012 @ 1:06 pm
The 50Hz frequency of the incandescent lights in the background causes a different exposure when the shutter speed is shorter than 1/100s. The bounce flash provides the same output in both pictures, correctly exposes the foreground and does not reach the far background because of the square law. The camera settings are the same, so it can only be the ambient light that has a different levels in the 2 pictures.
Damien
Comment by Damien — November 20, 2012 @ 1:07 pm
To further amend my comment (#56), the first shot was likely shot further from a wall than the second. Thus the falloff in the 2nd is stronger than in the first.
Comment by Rob — November 20, 2012 @ 1:09 pm
Different lens?
Comment by Michelle — November 20, 2012 @ 1:11 pm
Whoops.. just read that you didn’t change the flash direction. In that case, I think that the TTL setting was read from a different place in each shot, which give the flash a different output.
Comment by Ed — November 20, 2012 @ 1:12 pm
There’s no way your flash, however it was bounced, is reaching that back wall like in the first photo. That rules out any variables involving the flash positioning or modifier (which you verified in your followup). The faces are all properly exposed so ETTL did it’s job correctly. You didn’t drag the shutter to increase the ambient light since your exposure settings remained the same. The only way I can come up with for the difference in look from the first photo to the next is something about the ambient light in the room was changed from one photo to the next. Either someone turned off some lights or or pulled some curtains across a window or perhaps you had one of those freakish instances where you assistant was shooting somewhere closer to the back of the room and their flash went off at the exact moment yours did. That seems unlikely considering the quality and evenness of the light so I’m going with room lights/window or something like that changing.
Comment by Steve — November 20, 2012 @ 1:13 pm
You have used different focal length for the pictures. In the 1st picture you used a normal/tele length, and in the 2nd one you used a wide angle length.
That means you were further to the ladies on the 1st picture. So, your flash was fired with more power, thus illuminating better the background. Inverse square law.
Comment by Humberto Yoji — November 20, 2012 @ 1:13 pm
It appears the ambient light is different in each picture. Using the same settings for different levels of ambient will make the image darker or lighter.
Comment by Josh — November 20, 2012 @ 1:13 pm
zoomed flash head
Comment by Brani — November 20, 2012 @ 1:16 pm
Pic#1 had more ambient due to more daylight spilling in.
Comment by FrankS — November 20, 2012 @ 1:17 pm
It’s the angle you’re standing at. The background is brighter with the angled view, as the flash lights up the side wall. The straight on view with the chandelier in the middle, the flash can’t reach the length of the hall, so the far background is dark.
Comment by Nica — November 20, 2012 @ 1:19 pm
oh no.. wait.. just had yet another look at the iamges. The first image shot at an angle to the wall ‘behind you’, you turned 45 degrees to the subject, and the wall would then be slightly to your right. The second image, you stood square on to the subject, the same wall you used is now directly behind you, your flash is now pointing to the wall to your right. Hard to explain without a diagram, hope you got the jist of it! :)
Comment by Ed — November 20, 2012 @ 1:19 pm
The first one was bounced off a wall farther away from subject. The second one was bounced off the ceiling closer to the subject. Inverse square law in effect.
Comment by Kuttua — November 20, 2012 @ 1:20 pm
In the first one there is “less” wall at the background than in the second one. Since the wall is white, in the second one, TTL had to work a little less to illuminate the scene.
Comment by Felipe Curvello Anciaes — November 20, 2012 @ 1:20 pm
I’m going with a different focal length for the two shots. I had quickly scanned the comments and hadn’t seen that answer before, but just looking up a few comments now and see that Ryan had the same idea. Love your work Neil!!
Comment by Judy — November 20, 2012 @ 1:22 pm
You have changed your focal length on your zoom lens. This means to get the same shot (comparatively) you have also moved your distance to the subject. That means in terms of the inverse square law in your first shot (where you are zoomed in and further from the subject) the light is falling off less steeply. Thus a more balanced lighting.
The second shot you are closer to the subject – the inverse square law now is more acutely noticeable as the fall off is far steeper.
I know all this from an excellent earlier Tangents blog. Neil you are the best photo trainer out there!
Comment by Arthur — November 20, 2012 @ 1:26 pm
In the top one I believe you bounced from a wall that was farther from the subjects than the wall in the bottom shot. Due to the inverse square law, the falloff was much faster in the bottom shot.
Best regards,
Mic
Comment by Mic Ty — November 20, 2012 @ 1:32 pm
Ladies have the same flash exposure. Which means same flash setting, almost same angle of bouncing. The ambient exposure is changed. The fact that camera setting is same in terms of exposure, the only way to change the ambient exposure is that there is a “real” change in the ambient itself. Which means, in the first shot there were extra lights in the room, which is turned off in the second one, may be disco lights or whatever :-)
Comment by Saulat — November 20, 2012 @ 1:44 pm
Figure out when on flash was set a BL (backlit lighting) on and the second images was BL off?
Comment by Ondrej — November 20, 2012 @ 1:51 pm
The metering was thrown off due to the mirror at the back wall. Your first shot wasn’t pointed at the mirror, while the second shot was. More light got reflected from the mirror in the second shot and the TTL metering was affected.
Comment by David Hall — November 20, 2012 @ 1:52 pm
It appears that you have moved in the room and this has affected the way the flash provided light to the subjects.
Comment by Dave — November 20, 2012 @ 1:55 pm
I think the difference here is due to the TTL metering on the flash. The second image has more darker colored areas in it, tricking the camera’s meter, so the flash is given more power automatically, thus brightening the foreground to make up for it. This makes the ambient light exposed less compared to the first image.
Comment by Joe Marshall — November 20, 2012 @ 2:06 pm
Oh No! I just read I have to wait until November 26 to see the right answer!
Sounds like I need to go test my theory.
Thank you
Comment by John — November 20, 2012 @ 2:08 pm
Ah, this is easy peasy light fall off squeezy. First, the perspective of the people changes from one image to the next. Comparing the subject to the size of the windows indicated you changed their distance from the camera. When you are closer to your subjects, the light falls of quicker due to the inverse square law and the light source being close to the subject. Now, when you move further away, the light source is further from the subjects, and through the magic of the inverse square law, now lights the background more, even though the light source is coming from a greater distance. In a studio setting, or in manual flash, one would have to increase the flash power to maintain proper subject exposure. However, if your flash is in ETTL, the ettl will increase the power automatically.
Comment by Shane — November 20, 2012 @ 2:10 pm
Neil, the first is TTL BL. Flash is balanced well with ambient. The second one is just TTL act as main source of light..Am i right?
Comment by Glen — November 20, 2012 @ 2:10 pm
Two different focus points which affected the metering.
Comment by Patty Marchesi — November 20, 2012 @ 2:14 pm
Neil said:
“- I mentioned at the start that I used the same camera settings. I didn’t change the camera settings, nor the exposure mode of the camera.
- my flash was bounced in exactly the same way for both images. I didn’t change the angle. I didn’t change my light modifier.”
The most obvious thing that changed was Neil’s perspective. “Change the light by changing your own position” as Neil has spoken about it previously. (See http://neilvn.com/tangents/2011/04/26/ulorin-model-2/). Since Neil moved and the bridal party essentially did not move, the change in his position changed the direction of light from the bounce surface as far as the camera is concerned. (Since the inverse square law is always in effect, the direction of light alters how quickly certain objects in the background go dark.)
Comment by Stephen — November 20, 2012 @ 2:23 pm
You zoomed the flashed head more on the second one which bounced the light more directional then the first which was set to a wide zoom setting. I dunno lol.
Comment by kevin — November 20, 2012 @ 2:36 pm
It looks like you let in more light with your shutter (or by raising your ISO) in the first image.
Comment by Kristopher — November 20, 2012 @ 2:40 pm
Here goes….sorry if it goes on a bit.
In Pic 1 it looks as if you have bounced the flash 90 degrees to your right and slightly up towards the ceiling (see tell-tale shadow on ‘exit’ sign) throwing light into the room far end of the room due to the inverse square law.
You have said that you “used the same camera settings, didn’t change the camera settings, nor the exposure mode of the camera. The flash was bounced in exactly the same way for both images. You didn’t change the angle and didn’t change the light modifier”.
So in Pic 2 you have moved slightly to your right and turned slightly to your left so you are looking straight down the room. You say you haven’t changed the angle of bounce, so the flash is still pointing 90 degrees right and now bounces off the wall to your right, lighting the ladies more from the side (see girl in red and shadow caused be her arm – also shadow on jaw of girl holding flowers). The slightly harder looking light is again because of the inverse square law and the light being closer to the subjects.
That’s my guess. Am I hot or cold?
Comment by Colin — November 20, 2012 @ 2:58 pm
The first shot is as intended. In the second, something came between the flash and the wall; a curtain, sliding partition etc. or just a person.
Comment by Allen — November 20, 2012 @ 3:10 pm
The one is on camera flash, the other is off camera flash, thats not complicated..
Comment by anthony dillon — November 20, 2012 @ 3:18 pm
Based on your description, the only variables left are the lens & focal length.
Comment by Eric Franks — November 20, 2012 @ 3:19 pm
The second photograph was taken with a faster shutter speed. No other changes would be necessary to accomplish this effect.
The faster shutter reduces the amount which the ambient light contributes to the photograph, however your main subjects are still properly exposed due to the flash. Since the flash duration is far less than your shutter speed, changing shutter speeds does not impact the amount a light provided by the flash.
Comment by Shawn — November 20, 2012 @ 3:20 pm
Not reading any of the posts above me before I write this.
You using TTL. The second picture has two light sources in the frame so the camera decided it needed less flash.
One of the drawbacks to TTL, your camera makes decisions based on some Japanese engineer’s algorithms who has no idea you are shooting a wedding years later with a light in the frame.
Comment by Michael — November 20, 2012 @ 3:26 pm
1. If the aperture + Time + ISO stays constant, the ambient exposure stays constant.(Both = 1/160 @ f/4.5 @ 1600 ISO).
2. The only variables not mentioned are the power of the flash, focal length and distance to the subject. Increasing the power of the flash, will brighten the subject as well as the ambient light.
3. Moving closer to the subject will increase the power of the flash.
4. The 2 pictures were taken in different directions. The focal lenghts used are different. (Look at the chandelier) The perspective changed.
5. Moving closer to the subject increases the power of the flash (should power stay constant, and it increases the ambient exposure)
Comment by MvH — November 20, 2012 @ 3:26 pm
Did you change from holding the camera landscape to portrait?
Comment by Dave — November 20, 2012 @ 3:36 pm
Opps, I got ahead of myself and overlooked that the camera settings did not change. From the photo’s it looks like you and your subjects were standing much closer to the wall (or bounce target as stated above in post 110) behind you for the second shot, creating a much smaller “softbox” on the wall behind you as well as reducing the amount of light put out by the flash to properly expose your main subjects.
In the first shot, the flash would have spread out more before hitting the wall, creating the softer light as is seen. This distance would have also required the flash to put out much more power, providing more light to the rest of the room. The ratios of the distance between flash to subject and flash to back of the room would be much smaller in the second shot so the light fall off would be more apparent.
Comment by Shawn — November 20, 2012 @ 3:37 pm
Hi Neil,
Have been following your advice on all things flash related for a while now (see – http://www.photoed.co.uk/?p=220 – hope you don’t mind the shameless self-promotion).
Here’s my best shot at your brain teaser:
In both shots, the flash has been bounced off the wall behind the camera. The difference between the two images is the positioning of yourself and the group of people in the room.
In the first image, you have positioned yourself further into the room than in the second image. You are therefore further away from the wall used to bounce the flash. The light has had to travel further from the camera to get to the group of women, so the light fall-off from the subject to the background is reduced according to the inverse square law.
Also, in the first image, the group of women is positioned closer to the background than in the second image. Therefore, the effect of any light fall-off that is occuring has been minimised.
Both of these factors are working together to give a more even light on the subject and background in the first image.
Keep posting the great articles.
Comment by Edward Heseltine — November 20, 2012 @ 3:41 pm
you wanted a simple answer, more light was bounced off the walls on the right.
Comment by Julian — November 20, 2012 @ 3:46 pm
The first image was taken at a longer focal length and greater lens to subject distance. The flash head was most likely zoomed in, and because of the greater distance, resulted in more required flash power
The second image was taken at a wider focal length and shorter lens to subject distance. Conversely, the flash required less power for proper exposure, hence the darker background.
Comment by Bill — November 20, 2012 @ 3:49 pm
6. A longer focal length was used in the top picture, as can be seen with the higher compression. With the longer focal length you need to move further from the subject.
7. When you stand very close to the subject, the subjects are correctly exposed with TTL Flash, and the background received less light. (Inverse square law)
(Bottom picture)
8. As you move further away from the subject, the inverse square law changes between the camera / subject and background. The background (ambient exposure) benefits from the increased distance to your subject. The TTL flash releases more light to correctly expose the subject and the background benefits.
Comment by MvH — November 20, 2012 @ 3:56 pm
My take is the following (note that I haven’t read through all of the comments, so I may be repeating what someone else has already posted… my apologies if that’s the case – purely unintentional): you have slightly different POVs in both pictures. In the first (top), I suspect that the wall from which you are bouncing behind you is further away from you and your subjects. Therefore the relative distances from that light source from front to back of the picture is in the smaller spectrum (so you get more even lighting from to back). In the second (bottom) picture, the wall behind you is closer to you and your subjects. The relative distances are therefore more significant from a lighting perspective (inverse square law).
Comment by Denis Trudeau — November 20, 2012 @ 3:59 pm
in the second shot ur closer to the back wall behind u so the light fall off is faster due to the inverse square law, the first shot u were far enough away from the wall behind u that the light had to travel a much longer distance thereby slowing down the falloff
Comment by Naftoli — November 20, 2012 @ 4:04 pm
also in the second photo wall behind the girls is much further away than in the first photo
Comment by Naftoli — November 20, 2012 @ 4:07 pm
I’ll give it a try: Looking at the chandelier in the second photo, (and assuming you are using the same lens at the same focal length) you are further away from the subject and therefore less background ambient light is picked up when using the same camera settings for both pictures.
Comment by John Parker — November 20, 2012 @ 4:08 pm
Did somebody dim the room lights for the second shot?
Comment by Barry — November 20, 2012 @ 4:10 pm
On further reflection, it’s the perspective that changed. Neil’s position in the second shot is closer to the brides.
When standing closer, the ratio changes between distance-to-brides and distance-to-background-elements. Numbers to illustrate…
First shot:
distance-to-brides ~ 15feet
distance-to-background-elements ~ 35feet
15/35 = 0.43
… walk forward 10 feet, recompose …
Second shot:
distance-to-brides ~ 5feet
distance-to-background-elements ~ 25feet
5/25 = 0.2
Comment by Robert — November 20, 2012 @ 4:26 pm
In the first picture, you stand close to the wall behind you that is used to bounce the light, and your subject stand halfway between that wall and the background. The subject and the background are at a about similar distance from the wall being the source of light, both receive similar amount of light.
In the second picture, you and the subject stand close to the wall behind you that is used to bounce the light. Because the subject is close to you, you use a wide angle lens, because the subject is far from the background and close to the wall, the bounced light do not reach the background due to inverse square law.
Comment by Damien — November 20, 2012 @ 4:29 pm
Judging by the chandelier, the power on got turned low or your battery on your flash needs to be replaced.
Comment by Chris — November 20, 2012 @ 4:37 pm
Was it that one was a .jpg and the other you used the RAW file??
Comment by Dan Collett — November 20, 2012 @ 5:03 pm
Inverse square law
Comment by Matthew finnigan — November 20, 2012 @ 5:12 pm
Im going to say you shot the bottom shot first, you where standing at a large doorway or hallway. The flash was pointed behind you and bounced off maybe part of the wall.
you then repositioned yourself to the left where away from the doorway or hallway and had your back (and Flash with BFT facing the wall behind you then zoomed in tighter and KAPOW! you got the shot.
Comment by Hector Gomez — November 20, 2012 @ 5:12 pm
I believe the top image is bouncing from the corner of the room so it is getting two walls and a ceiling. The bottom image is primarily one wall and the ceiling.
Comment by Matt — November 20, 2012 @ 5:27 pm
I’d say if nothing you were doing changed, the simply the environment changed.
Something moved or blocked the surface you were bouncing the flash off of.
isn’t this fun? :-)
Kevin
Comment by Kevin Lloyd — November 20, 2012 @ 5:35 pm
You pointed the camera into a different direction?
e.g. for the 2nd picture you took one or two steps to the right so you’d be shooting against some other part of the room which changes the light in the backdrop and the TTL calculation?
Comment by Sam — November 20, 2012 @ 5:40 pm
You change positions in relation to your subject, top allowing more ambient light and the bottom one less.
Comment by Robert — November 20, 2012 @ 5:42 pm
Hi, my guess is, the angle changed as well as the distance the light has to travel for the exposure?
Comment by Retha — November 20, 2012 @ 5:43 pm
Or bounced backwards and then bounced forwards?
Comment by Retha — November 20, 2012 @ 5:49 pm
I think the reason for the difference in ambient light levels is that in the first shot the women are much further from your bounce surface (wall) than in the second shot. In the first shot, you take advantage of the ‘inverse square law’ so the background and the participants are nearly the same distance from the light source (the wall), whereas in the second shot, the participants are close to the light source, but the background is much further away from it. Thanks,
Comment by Brian Bullock — November 20, 2012 @ 5:50 pm
adding to my comment (91), I’m pretty sure I’m right, this can be confirmed by the lines on the ceiling :)
Comment by Ed — November 20, 2012 @ 5:55 pm
In the second done you had your tongue out?
Comment by Russ — November 20, 2012 @ 6:00 pm
EC exposure compensation
Comment by vbelo — November 20, 2012 @ 6:01 pm
Either the distance between the camera and the subject changed meaning that the inverse square law applies or the medium against which you bounced the flash changed since the wall/ceiling/object off which you bounce the flash will have a large impact on the type of light reflected on the subject.
Comment by David Sexton — November 20, 2012 @ 6:01 pm
Spot meter vs matrix.
Comment by Judene Gardner — November 20, 2012 @ 6:10 pm
Four words…Inverse Square Law Baby!!!
Comment by Jeff Kernen — November 20, 2012 @ 6:26 pm
Comment by Neil vN — November 20, 2012 @ 6:31 pm
The issue is simply, that the first image was taken with tonality being lifted up more due to the presence of more ambient light from the background as well as the walls being closer hence the combination of ratio flash + ambient light created less contrast resulting in the added bonus of the flash illuminating parts of the background as well as the subject.
The second image resulted in a darker rendition because there is now less ambient light exposure due to ‘depth’ and distance of the background to the camera resulting in the background going dark plus the relative absence of a close surface for the bounce flash so only the subject is illuminated.
Ultimately, the subjects simply walked further INWARDS in the venue than the first image resulting in different tonality/rendition due to less ‘radiosity’.
Comment by Arnold Gallardo — November 20, 2012 @ 6:37 pm
In the first one the light was bounced into the corner of a room (that was behind you), in the second image the light was bounced into a wall behind you. The surface area of the corner is larger and the perpendicular angles of the corner give a wider spread of light.
Comment by Mar H — November 20, 2012 @ 6:40 pm
In the first image, the light is coming from camera position (stofen?), while in the second image, the light is coming from camera right (likely bounced from camera position and flagged).
Comment by Dajuan — November 20, 2012 @ 6:42 pm
Well, Neil… i guess that if you added lens type and focal length details it would be much easier…
The feeling is like in the 1st photo you are farther from the girls (i hate to call’ em “subject..) so the inverse square law makes its job; at first look i would have said that in the 2nd photo an eventual remote flash, placed at the opposite side of the room, did not fire… but looking a bit “closer” i think that no remote flash could ever do that shadows-softening work on girls’ faces… it could only brighten the walls and ceiling… yes, i place my cent on change of distance….!!! (from girls, not subject…)
Comment by Carlo — November 20, 2012 @ 6:43 pm
Comment by Neil vN — November 20, 2012 @ 6:50 pm
You didn’t change the angle of the flash or the exposure mode of the camera. The flash was in the same position and the light modifier was in the same position (relative to the camera).
You changed position in the room. You are near a wall (behind you), but in the first shot you are shooting at an angle to the wall, maybe 45 degrees. The flash is positioned behind you and to the left of your shooting angle. There is a flag on the flash that directs it toward the wall, but at some distance from you so the flash is illuminating much of the room by bouncing off a distant part of the wall.
In the second shot you are shooting perpendicular to the wall behind you. The flash is now hitting the wall closer to the foreground so there is more light on the women in front. The camera adjusts the exposure so the background is now dark.
Diagram at http://small-farm.org/Shotpuzzle.jpg
Comment by Dwight — November 20, 2012 @ 6:55 pm
The distance from the camera to the background changed. One time the group was in front of closer side wall for the background the next the far back wall was the background and was darker because of greater distance and light fall off.
Comment by Judene Gardner — November 20, 2012 @ 7:01 pm
I think the difference is down to the inclusion of two bright chandeliers in the first frame and less incandescent lights in the second. The ttl flash needed to supplement the ambient exposure in the first frame is less than that in the second due to the presence of bright ambient lights in the first frame. These points of light combined with a return of the flash on the persons in the foreground of the first exposure have caused the flash duration and power to be stymied to prevent over exposure. In the second frame again there is good flash return from the foreground subjects without a great amount of background ambient light adding to the exposure – leading the ttl flash to create a more even exposure without the risk of over exposure.
Comment by Phil B — November 20, 2012 @ 7:02 pm
Oooppppssss read first frame as second frame and vice versa in my comment : )
Comment by Phil B — November 20, 2012 @ 7:05 pm
Hi Neil, since you used TTL, my thinking is that in the first photo, the image has less contrast whereas in the second photo, you’re picking more of the dark shadow down the hall way and the chandelier is farther away. The result is, the second photo looks ‘darker’ to the camera so it blasts out more light. The second, the tones are more even so the flash outputs a little bit less light and the image doesn’t look as contrasty/harsh.
Comment by Bill — November 20, 2012 @ 7:06 pm
I didn’t read any of the other comments, so this may have already been discussed, but is the difference just ttl vs manual? I have been doing OCF ttl and I often get mixed results with the same settings, but I have heard that if you use the flash in manual you have more consistent results.
Comment by Stacey Hemeyer — November 20, 2012 @ 7:09 pm
You changed your position. In the first shot the wall in the background looks like a mirror and in the second shot it’s not there.
Comment by Steve Pestrock — November 20, 2012 @ 7:10 pm
On the first shot you used Matrix Metering mode and on the second one Spot metering mode.
Comment by Daniel Ruiz — November 20, 2012 @ 7:12 pm
You changed your position, so on the second photo there is no wall infront of you to bounce the light back. Thats why the background on the second one is darker.
Comment by Ivo Popov — November 20, 2012 @ 7:18 pm
My guess is the first one had the flash in TTL-BL mode and the 2nd was in standard TTL
Comment by Matt — November 20, 2012 @ 7:20 pm
to me it looks as though the lights on the side of the top picture added a bit more ambient light, where as the bottom photo was taken from a slightly different position (looking down the room instead of towards the lights on the wall in the background).
Comment by Anthony — November 20, 2012 @ 7:29 pm
Some interesting answers so far hope mine is not too simple,
I think the battery’s had not fully recharged.
good luck to everyone!
Comment by Jamie Welsh — November 20, 2012 @ 7:40 pm
Hi Neil, I think you just changed your position!
Comment by Eduardo B. — November 20, 2012 @ 7:42 pm
Initially i thought it was perhaps a spot metering error where the spot was on the blue dress in one image and the white flowers in the other. However, It appears to my untrained eye that the flash portion of both images (the subjects skin) remains constant but the ambient (or at least the background) has dropped by such an amount to rule this out or any inverse square law trickery caused by bouncing off different surfaces. Therefore I conclude that either the brighter images was taken just as another camera and flash went off or the darker image was taken after someone turned out the lights!!! ;)
Comment by Steve — November 20, 2012 @ 7:43 pm
Hi,
I don’t have time to read all the comments, so sorry if this has already been suggested: Is it that the flash to subject distance was greater in the first shot, meaning less dramatic light fall off?
Comment by Dylan Jefferis — November 20, 2012 @ 7:47 pm
You changed the angle of the bounce and/or changed the quality of the light on the flash using a diffuser. In the first case, you have more diffuse light that seems to also be directed more uniformly around the room so that the background is getting light from the flash. This may have been done with a stofen and/ or by having the bounce at an angle of less than straight up (at 60 degrees, maybe). In the second photo, the light looks like it was bounced straight up on the ceiling so it created more harsh shadows under people’s chins and the light did not make it into the back of the room.
Comment by Barry — November 20, 2012 @ 8:12 pm
I have to agree with Jamie Welsh battery’s had not fully recharged
Comment by Harold Horlback — November 20, 2012 @ 8:19 pm
do we really have to wait almost a week to find out the answer to this? LOL!
Comment by Mandy — November 20, 2012 @ 8:21 pm
Guessing that while the angle didn’t change, in the second shot you’re closer to the surface being bounced from, so the inverse square doesn’t work in your favour as much.
Comment by Dave — November 20, 2012 @ 8:39 pm
I read through the posts to see if anyone was thinking the same thing I was and first one that had the same idea was Tad in #71. My guess is the same— someone walked between the flash and the bounce wall causing the TTL to compensate.
I’ve read most of your site and bought your book. Posts like this are great to get the reader actively engaged in the kind of problem solving they’ll likely have to do when shooting in the field. Thanks for all you contribute to sharing the art & craft!
Comment by Scott — November 20, 2012 @ 8:51 pm
I think that both images were taken at different times. In the first picture it shows the presence of sunlight entering the room, along with the light from the lamps. In the second image shows up only the side walls lamps and hanging lamps are helping the flash to illuminate the scene, so the room looks darker.
Comment by Alfredo Medina — November 20, 2012 @ 9:19 pm
To expand on my answer in comment #80 (I.E. the lights were turned up)
(1) The exposure of the people are about the same in both images – a bit brighter in the first one though
(2) The camera exposure settings weren’t changed
(3) The background (ambient) lights look much brighter in the first one – see especially the wall lights. As the exposure settings didn’t change – the only way for this to happen is for someone to turn up the room lights. This brightens the background and also slightly increases the brightness of the people in the first image (though the main contributor to their exposure is still the bounced flash).
The shadows are also softer – probably due to increased fill from ambient – or maybe a slightly different bounce surface.
Comment by Frank Courtney — November 20, 2012 @ 9:30 pm
I’d say on both shots the flash is angled at about 45 degree, the only difference is the wall on the right.
On the first shot, the camera/ flash was slightly facing the wall on the right eventhough it was not perpendicular to the wall.
The ceiling and the wall on the right helped to bounce the light off to lighten the ambience.
On the second shot, the flash was bounced to the ceiling only (the same way as the first shot) but there was no other media to bounce off. The light would just fall off as it travelled the room without having any impact to the exposure.
Comment by Bob — November 20, 2012 @ 9:33 pm
On the 1st. photo the wall on the back reflected the light from the flash
Comment by vbelo — November 20, 2012 @ 9:34 pm
The distance to the bounce surface is different. This will affect why there is more mpact of the flash on lighting then on one versus the other.
Comment by Matt — November 20, 2012 @ 10:01 pm
Hello Neil,
Here’s my guess – The difference between the two photos is due to the positioning of the flash head. It looks like the flash from the first picture bounced from the wall. The flash head was facing upward above your right shoulder. The second picture shows darker background because the flash head was facing the front-left of the camera and the lens was able to see the pre-flash, thinking that it needed to tone down its flash output a bit.
By the way, I love your work… and I constantly learn from your website. I also use CTS and the BFT indoors when needed.
-Joel
Comment by joel alonzo — November 20, 2012 @ 10:09 pm
If the settings in both images were the same, the only reason for the difference is the ambient light. I think that the TTL flash is not the main factor, because the subjects are the same, with identical brightness in both images. So, in the first image, the ambient light is brighter than the second one. The TTL flash compenses that difference getting the same exposure in the subjects, but obviously it does not affect to the background.
Comment by Rodrigo Pizarro — November 20, 2012 @ 10:31 pm
The pictures were taken at different angles which means that you bounced your flash on two different surfaces: mirror and floral wall.
Comment by Joel V — November 20, 2012 @ 10:32 pm
I’m guessing it has to do with the inverse square law. In the first image you were zooming from a further distance from the subjects, causing the difference in foreground and background exposure to be less dramatic. While the second image you were closer to the subject with a shorter zoom length, causing the more dramatic light falloff.
Comment by Timothy — November 20, 2012 @ 10:35 pm
Neil,
I will be the first to say that I have no idea why the two photos look different. In fact, I’ve often experienced frustration after reading a few of your articles and thinking, ‘I’VE GOT IT!’ only to discover I may in fact have had it, but apparently left it at home.
THUSLY: due to my lack of knowing, I think I would qualify most for a one on one session with you over someone who does in fact know the answer to your puzzler. Why would they need help? THEY HAVE IT!
However, I envision a skype session with you to go as follows:
ME: “Hi Neil, love your stuff”
YOU: “Thanks, so… what would you like to discuss?”
ME: “Hrrrrm… what is inverse square rule/law thing?”
YOU: *gnashing teeth* “Oh, you might have missed that bit where I explained on my website”
ME: “No, I saw it, but you linked somewhere else and I was too lazy to click that link”
YOU: “You mean the link where I stated that if you don’t have the basics down you might need to start here?”
ME: “Yeah, something like that.”
*silence*
ME: “Did you see my website?”
YOU: “Yeah, its… it’s… well, its on the internet, now, isn’t it? That’s a feat in itself!”
ME: “Really? Awesome!”
YOU: “Oh! You know, I’ve just remembered I need to have the air pressure checked on my tires. Thanks for participating in the contest!”
ME: “Thanks, Neil!”
So. There you have it.
I have my suspicions as to why the two images are different, but seeing as how I never get the same results twice, I’d be lying if I said I were confident with my answer.
Honesty must count toward something, yes?
(Don’t you hate this internet format pattern of beginning a new ‘paragraph’ after only typing a single sentence? I do.)
Comment by Donny — November 20, 2012 @ 10:47 pm
You moved yourself to a different position
Comment by Karen — November 20, 2012 @ 11:05 pm
I think the brighter one is set to rear sync. I scanned the answers and don’t think I saw that yet.
Comment by Dana — November 20, 2012 @ 11:21 pm
The only way to get more ambient light into the background is to let more light into the camera. Since you say you didn’t changed the aperture or speed or ISO you changed the flash setting. You changed the flash setting from normal to REAR or SLOW to let more light in before or after the flash fired.
Comment by Don Tod — November 20, 2012 @ 11:21 pm
If, as you say, you did not make any great changes to the camera or flash then the only other option left is that something occurred which suddenly change the ambient light in the back of the room.
Your camera was on manual so it did not adjust for the change (hence the settings stayed the same), the flash was TTL exposing based on metering the girls in front of you so it only flashed enough power to light them (so it didn’t change exposure due to the background change).
Perhaps a door/curtain was opened/closed (allowing daylight in) or maybe other lights were switched on/off?
Comment by WTf4Photography — November 20, 2012 @ 11:26 pm
Focal length change and distance from the subject changed. Moved further away, smaller light source, harder shadows, inverse square law light falls off quicker.
I’m probably wrong though…
Comment by Ryan Harvey — November 20, 2012 @ 11:26 pm
Since you didn’t modified any settings on the camera, you probably did on the flash. Slow Sync Mode on the flash its probably the reason why the first shot looks more balanced.
Comment by Daniel Ruiz — November 20, 2012 @ 11:39 pm
Hi Neil, lots of comments and mixed all of them. For me the correct answer is you zoomed in the flash between shots.
Thanks for the brain teaser….I hope this is not gonna be the last one since you have had such a great response!
Regards,
Mauricio
Comment by Mauricio — November 20, 2012 @ 11:47 pm
Hi Neil,
I think it is other side of hall – everyone has turned around 180 deg – so it is different background.
Thanks for the wonderful site – I learn a lot from your site and pictures I have taken recently are being admired a lot !
Regards
Comment by Mudit — November 21, 2012 @ 12:01 am
I’m thinking of the effect of the Inverse Square thingy and probably the distance of the background that made the difference between the two shots.
Comment by Angelo Chiu — November 21, 2012 @ 12:29 am
The answer is simple as you’ve stated. Assuming you’re using the exact same lens, you are actually closer to your subject in the first picture and slightly to the left of the subject (see chandelier is top left in this frame). I’m assuming that w/o changing flash settings (zoom on flash) that you’re bouncing backwards off of the back wall, maybe some of the ceiling and part another wall to the left of you. This is diffusing the flash light a lot allowing for good mix with the ambient. In the second picture, you are now directly in front of your subject (see chandelier is now directly above her) and farther back which brings you closer to the wall. I’m going to guess that you are now bouncing off of a smaller area (since you’re closer to the wall) which means less diffusion and more concentrated light on the subjects closest to you which “kills” the ambient light in a sense.
Comment by John — November 21, 2012 @ 12:35 am
1] The light reading was taking for the background and set manually. The flash TTL will adjust itself as needed for the forground where you aim your camera.
2) The flash was blocked and did not fully bounced
Comment by kirubel — November 21, 2012 @ 1:33 am
Zoom the flash head from 24mm to 200mm.
Comment by Jonathan Liaw — November 21, 2012 @ 1:36 am
Easy, and I have learned it the hard way on the field, it has nothing to do with your flash, you have used the flash the same way for both images. The only difference is that you allow more ambient light reach the sensor for the first image, by any of these methods: cranking up the ISO, slow down the shutter, widened the aperture.
Comment by Tumpal — November 21, 2012 @ 2:19 am
ouch, I didn’t read your explanation carefully…
Comment by Tumpal — November 21, 2012 @ 2:23 am
Flash was bounced from a wall on your right, in the top pic the flesh tones from the woman on the right on the pic caused the flash to “kill” itself quicker due to the light reflected back, allowing for more ambient light to register ?? Just a though and i have had a couple of Scotches !!
PS as mentioned before , great site and im sure io speak for everyone when i say thank you for your invaluable insight and help !
Comment by Dickie Gill — November 21, 2012 @ 2:28 am
I haven’t read through the guesses but I have been on your site for at least 15 minutes, and the answer is easy. You flagged the flash. If the TTL is the variable, the only way it could change is if it’s getting a different reading. Great method, btw. Can’t wait to try it.
Comment by Brian Anthony — November 21, 2012 @ 2:39 am
Hi!
I think difference is because there is more ambient light registered by TTL system on second image and flash is fired with less power.
Sincerely, Andrey Mitin
Comment by AMitin — November 21, 2012 @ 2:49 am
Comment by Neil vN — November 21, 2012 @ 2:54 am
Then to complete my explanation from 95 – due to the shortened camera distance to subject in the second shot the TTL didn’t require to give out more light from the flash. Thus there has been less light given out to the room. This combined with the effect of ISL gives a darker room. – as it is the flash that has been boosting the ambient.
Comment by Arthur — November 21, 2012 @ 3:21 am
because the shutter speed are different. faster shutter will result in background darker and shower shutter will result in background brighter.
Comment by Jack — November 21, 2012 @ 3:32 am
You bumped up the ISO.
Comment by Marcus Wong — November 21, 2012 @ 3:36 am
Apologies…missed the part on the constant ISO.
Comment by Marcus Wong — November 21, 2012 @ 3:44 am
OK to further add to my comment #161, TTL-BL will try and evenly light the whole scene (as in shot 1) whereas standard TTL is only interested in the subject in the centre of the frame, hence the darker background in the 2nd shot
Comment by Matt — November 21, 2012 @ 3:49 am
189.Hi Neil,
I think it is other side of hall – everyone has turned around 180 deg – so it is different background.
Thanks for the wonderful site – I learn a lot from your site and pictures I have taken recently are being admired a lot !
Regards
PS : And mirrored the image
Comment by Mudit — November 21, 2012 @ 3:58 am
Maybe it is a different time of the day – ambient light from outside has gone down.
Comment by Mudit — November 21, 2012 @ 4:08 am
I haven’t read through all 206 replies yet but I am throwing this in for good measure… the settings on the camera haven’t changed and neither has your modifier. The only thing that could effect this is the ambient. I think therefore that you have a large window behind you and the sun was out in one and behind a cloud for the other!
That’s a simple explanation is it not? :)
Comment by Jon Lloyd — November 21, 2012 @ 4:55 am
It does appear the inverse square law affects the image, but not because you moved forward or backwards. However, the bounce source did change. I think you may have had an overhang of some sorts, perhaps a doorway or arch, behind you in the second image. This would have reduced the distance of your lighting source creating the more drastic light fall off. Your position is different in the first image. The overhang/doorway/arch no longer comes into play; the bounce surface is further away; therefore, light fall off is extended illuminating the background.
Tony
Comment by Tony Wooten — November 21, 2012 @ 5:24 am
Hi Neil.
The only thing that has changed is your body angle in each shot. I guess the flash was positioned to the right and behind you, probably with my favorite of your flash mods the black foamy thing, and set to ttl mode. It’s all to do with the inverse square law that I’ve almost got the hang of. With the first shot the flash is pointing into the rest of the room behind you with greater distance so giving a much softer and more even light ,but in the second shot your body has turned 45 degrees and that now means the flash is bouncing of the closer wall on the right of you. Less distance so faster light drop off.
Comment by Jay Stock — November 21, 2012 @ 5:26 am
I failed to sum up comment #208 — the bounce source is further away in the first image, and closer in the second.
Tony
Comment by Tony Wooten — November 21, 2012 @ 5:30 am
In the second picture, you moved backwards because the bridemaids came towards you. In the new frame you had brighter sources of available light (the light coming from the arches/windows and the light from both the chandeliers). So, the TTL metering was fooled, giving a smaller output for the bounced flash. The bridemaids moving towards you, they are closer to the main source of light (the wall behind you). That’s why they are lit harder than in the first image. And that’s why you had to zoom out, in order to catch them all in the frame.
Comment by Calin Botez — November 21, 2012 @ 5:40 am
I haven’t read all the comments, but my first guess would be the 2 dresses in the first shot that are not in the 2nd. Namely the lady in black and the lady with the black/white pattern dress.
Depending on the exposure mode, these “blacks” would move the exposure calculation more to the right, so the flash would expose more to get the 18% average. Whereas in the 2nd pic, they are not there (more “average” exposure) and hence the exposure calculation is more towards the left, so less flash light.
Hope what I am thinking comes out right in words.
Comment by Dave — November 21, 2012 @ 6:04 am
And perhaps the same can be said of the “light” in the room, contributing different amounts to the exposure calculation due to it’s position in the frame.
Comment by Dave — November 21, 2012 @ 6:11 am
198 Hi, Neil.
In the second picture two large chandeliers were in the frame. I think that this is the reason that the TTL system decided that you need less light from the flash.
Sincerely, Andrey Mitin
Comment by AMitin — November 21, 2012 @ 7:24 am
The one was taken with “BL” set in the flash, the other not
Comment by Johan Schmidt — November 21, 2012 @ 7:56 am
The difference is due to not having changed the parameters accordingly to te different exposure in the bottom picture.
Surely enough the shutter needed some dragging to bring the necessary light in to balance that black background.
Comment by Andrea — November 21, 2012 @ 8:51 am
Hi Neil,
I’d say you’ve exposed for the background and that your flash head is positioned more or less to bounce behind you/to the right of you.
In pic one, the bounced light is not spilling/reflecting off the ceiling in the right of the pic… the light is fairly even in the background…so the camera is reading the soft ambiant light of the whole room.
In pic two, you have moved your position, and the bounced light is now spilling/reflecting off the ceiling in the left of the image. The camera is reading the ceiling as the dominant ambiant light – and so, the rest of the room is dark.
Am learning so much from your site…thanks for your generousity.
A fellow Safrican :)
Comment by Theresa — November 21, 2012 @ 8:51 am
The exposure of the subject, the bride, is approximately equal in both photographs. However, the light fall off is a lot more dramatic in the SECOND image. While the lens focal length may be different for the two photos (based on the assumption that focal length is a lens setting and not a camera setting) I do NOT think this is the reason for the difference in the background lighting. I would say that it has to do with where the source of light is coming from. In both photos the flash was bounced. So the source of light theoretically becomes the wall (or object) that the flash was bounced off. In the first photo the room is at an angle to the camera viewpoint whereas in the second image it is directly in-line with the room. So it suggests a different surface was used to bounce the flash. In the first image the bounce surface was relatively far away from the subject. In the second image the source of light (once again this implies the bounce surface) was a lot closer. Due to the inverse square law the fall off would be much greater in the second image. I think the key point to realise is that the source of light illuminating the subject is coming from the bounce surface. So, for example, if the subject remained static while the photographer was moving back and forth, but keeping the subject the same size in the frame by zooming, the exposure (subject and background) would not change in relation to each other as long as the bounce surface was the same fixed distance from the subject. If, however, the flash was then rotated and bounced off a wall further away from the subject, the exposure relationship between the subject and background would change (with the background appearing lighter in this instance). Vice versa if the bounce surface was closer to the subject the background would appear darker. All due to the inverse square law.
Comment by Martin — November 21, 2012 @ 9:41 am
I would say that in one picture your closer and in the other your farther away. Hence, the flash drop off.
Comment by Roger Haataja — November 21, 2012 @ 9:43 am
Another thing that could of changed is, that the room light was lowered, so that is why one of the images has a darker background.
Comment by Roger Haataja — November 21, 2012 @ 9:55 am
my first guess would be that you changed the metering mode from EV to Spot or on the flash from TTl to TTLBL, but if that isn’t the case, then my guess is that by framing the bulbs of the chandelier out of the shot , the flash allowed more background light to show up in the frame. Oh heck..on looking again…on the second shot you were aiming directly at the large mirror at the back of the room. This may have reflected light back into the flash sensor telling it to back off.
Comment by Tim Shahady — November 21, 2012 @ 9:58 am
I suspect the BFT is the key. In the first shot, the subjects were illuminated with direct “spill” light from the flas and in the second shot the subjects were protected from direct light with the flag (BFT).
Comment by Rick — November 21, 2012 @ 10:11 am
? TWO Flashes
At the other end of the room, a SECOND remote flash was shot through the window (from the outside) to simulate window light. In photo #2, the remote flash did not fire.
Happy Thanksgiving!
Comment by ken — November 21, 2012 @ 10:24 am
Black Foamie thing!
Comment by Corinne — November 21, 2012 @ 10:44 am
I haven’t read any of the other comments yet, but by looking at the photos, the bottom photo (where you are a little bit more centered in the room) shows what looks like arched windows to the left of the photo. By positioning yourself in the top photo, you are getting some of the ambient light from the windows onto the subjects and the wall behind them.
Comment by Julie — November 21, 2012 @ 10:57 am
Well they were taken moments apart so i am figuring you did not have much time to change alot. looks like there was a mirror in the back that might have given the ttl a run for its money you moved a bit for the second one and had an angel so the mirror was now out of play
Comment by louis — November 21, 2012 @ 11:12 am
Neil,
I can think of two possibilities
1. The Flash zoom level is different in these two shots resulting in sharper fall-off in the second shot
2. The first shot is towards the wall on the right which is adding extra bounce(although weak) to further light up the ambient at the back side at an angle. The second shot is towards the long end of the room and no additional secondary bounce object to illuminate the ambient.
Cheers
Ani
Comment by Anirban Acharya — November 21, 2012 @ 11:14 am
Top photo shot with a longer lens, so less of the dark background shows. May also be a slightly higher angle cropping out the dark ceiling.
John Rogers
Comment by John Rogers — November 21, 2012 @ 12:24 pm
On the off chance I am one of those with a partially correct explanation, I’ll expand on my original comment (#44), which reads: “In the second image, someone blocked Neil’s flash by walking in between the flash and the rest of the room. This person effectively became the ‘light source’ instead of the wall.”
The general idea is that something inadvertently blocked Neil’s flash, potentially a guest at the reception. Whatever it was that blocked the flash, it provided a much smaller reflective surface than would have been available had the flash been allowed to bounce off the walls and ceiling. And this smaller light source doesn’t allow the light to travel to the back of the room as it does in the first image.
Comment by Justin — November 21, 2012 @ 12:55 pm
You had one of those flukey chances where another photographer’s flash went off and illuminated your shot so the TTL told the flash that the subject was illuminated so it only put out minimal power. Basically the shot was lit by another photographer for that brief moment in time.
Comment by Arthur — November 21, 2012 @ 1:12 pm
Since the only thing that can change the ambient light exposure when you don’t change the camera settings is the amount of ambient light, then the difference must be due to how much ambient light was available. Since it is day time (based on bright windows in back), I would guess that a change in the amount of sunlight coming in due to a cloud change or similar would be the reason.
I’ve answered this without looking at others’ answers for my own edification and in the spirit of the contest.
Since I doubt you’ll credit 2 guesses, I’ll leave a second alternative just for fun: someone else’s flash went off at the same time in the back.
Comment by Art — November 21, 2012 @ 1:16 pm
Here’s my guess. In the top photo the TTL system sees a darker scene because you don’t have the brightest parts of the chandeliers in the frame therefore more flash output. In the bottom photo you have moved to your right and included the two bright chandeliers in the frame. Now the TTL system sees a bright scene and therefore less flash output causing the darker background. The people are well exposed in the bottom frame because of their proximity to the bounced light which drops off quickly again giving the darker background.
Comment by Raul Longoria — November 21, 2012 @ 1:19 pm
Hi Neill
I think you zoomed your lens in the first shot to exclude most of the chandeliers,so less light hitting your camera sensor to effect your ambient exposure, then you zoomed wider in the second shot and more light coming in from the chandeliers caused the darker ambient.
Comment by Gerry Kelly — November 21, 2012 @ 1:19 pm
Shot in TTL so you were using centerweighted metering. The shift in the framing to include the chandelier dead center, plus the step back from the flower-catcher in #2, caused TTL to put out less power.
Alternative: flash didn’t have time to fully recycle and fired at less than full power.
Comment by Nick — November 21, 2012 @ 1:28 pm
Here are my observations:
* Both images show similar exposure for the foreground (the girls).
* There is a drastic light fall-off in Image #2 towards the back ground.
Based on what I understand about light
Comment by Viky — November 21, 2012 @ 1:36 pm
Here goes with my answer. The top one is using the flash in manual mode. The bottom image is using flash in TTL mode, as the flash will only fire enough light to light the subject. Where as using the flash in manual mode, you can get more or less light without having to change your camera settings. And in this occasion, you opted for more light to help fill the background.
Comment by Gary Smith — November 21, 2012 @ 1:36 pm
Flash recycle was slowdown…
Comment by AT — November 21, 2012 @ 1:41 pm
I guess if I read the entire question, I would know that both shots were done using TTL flash. So, my proper answer is that due to the shift in shooting angle, your position changed and therefore your background did too.
I would say that the top shot was that you were further away from your bounce source, which would have thrown more light back and therefore lit up the background.
The bottom shot you were closer, and therefore the flash didn’t need to work so hard in illuminating the foreground.
Fingers crossed.
Comment by Gary Smith — November 21, 2012 @ 1:43 pm
I think the change in flash coverage is due to a different zoom lens setting. For the bottom photo you use a wider setting and by doing so the flash wasn’t able to cover as much.
Comment by Martial — November 21, 2012 @ 1:45 pm
1st shot: Wide angle lens – you went close to subject. (shorter subject Distance to bounce Flash)
2nd Shot: Tele lens – Stood little far from the subject with similar framing.(Longer subject Distance to bounce Flash)
Rest ISO, Shutter Speed, aperture,flash output & Direction – remained constant.
Comment by Parthiban T — November 21, 2012 @ 1:45 pm
Here are my observations:
* Both images show similar exposure for the foreground (the girls).
* There is a drastic light fall-off in Image #2 towards the background.
Based on my understanding the difference in the background exposure is due to the distance between your flash and the bounce surface/(or wall).
The bounce surface in Image #1 (brighter background) is farther away from your flash than in Image #2.
In other words, if we consider the bounce surface as the light source (LS), the ratio of (subject distance)/(background distance) with respect to ‘LS’ is greater in Image#1 than in Image#2
Comment by Viky — November 21, 2012 @ 1:52 pm
Also important,I would add that by using a wider setting you had to get closer to the main subjects to get the same framing, and by doing so the TTL flash did not have to send as much light, hence a more localized lighting area.
Comment by Martial — November 21, 2012 @ 1:54 pm
As a few people suggested at the beginning (and I suspect many more after that), the difference most possibly lies on the distance of the surface that the flash light bounced on. First image, far – second image, close.
Comment by Iosif — November 21, 2012 @ 2:15 pm
In the first photo the lights in the room were brighter or turned on compared to the second photo where most of the lights were off or dimmed low.
Comment by Joram Freudenfels — November 21, 2012 @ 2:24 pm
Since all settings and modifiers are the same, the ambient light must have increased for 1678 aver 1681. Could be for several reasons, maybe the videographer turned on lights in the BG? The sun came out from behind a cloud?
Comment by Rob — November 21, 2012 @ 2:25 pm
Comment by Neil vN — November 21, 2012 @ 2:26 pm
OK – so based on your comment #246 – my original explanation (change in ambient) is wrong – hmmmm.
As the camera settings and the ambient light are fixed, then the difference must be due to the light from the flash. This can be one of three things –
(1) the surface bounced off in the first image is lighter or at a better angle for lighting the room or
(2) You added positive FEC or
(3) You metered off a different (darker) area – even though the camera settings are fixed, the metering would adjust the flash output
Thought I had it – really interested now to see the correct answer
Comment by Frank Courtney — November 21, 2012 @ 3:02 pm
It looks like that room has mirrors all over it (based on the top picture , and from the reflection in the ceiling next to the chandelier) you hit that slightly different than it did hitting the wall. So you change your overall angle slightly, but not the relative angle of the camera to the flash. You effectively have a smaller light source in the darker background picture with sharper falloff.
Comment by Chris Aldridge — November 21, 2012 @ 3:08 pm
It seems that the height position and level of the camera/ flash are different for both shots.
Since the flash contributes to the ambient light levels: 1) In the first picture, the camera appears to be at face level and this contributes to the bounce flash reaching past the crowd on to the walls. 2) In the second picture, the camera appears to be at chest level shooting upwards and this contributes to the bounce flash only reaching the first few rows of the crowd.
The angle and height at which the camera was used impacts the balance between the ambient light and flash mix.
Comment by Alex Lopez — November 21, 2012 @ 3:28 pm
I can think of two simple reasons:
1) Metering change. You changed from spot to center weight tp matrix or simply just metered on a different location using spot metering.
2) Batteries were low and the flash wasn’t able to fully reload before you took the second shot.
Comment by Winnie — November 21, 2012 @ 3:29 pm
I would say that your flash has not fired in the second image just giving us ambient light. Jack.
Comment by Jack — November 21, 2012 @ 3:43 pm
To add to my previous comment… A waitress wearing a white shirt walked behind you and became the “softbox” accounting for the reduced range and shadow on the right side of the ceiling.
Comment by Allen — November 21, 2012 @ 4:00 pm
Obviously it could be anyone with light coloured clothing, but the reduced size of the light source would explain the harsher shadows.
Comment by Allen — November 21, 2012 @ 4:10 pm
Light direction appears to be the same (celing bounced flash).
However, the first photo has a CTO gel on the strobe (to match the ambient background light), the second appears to be without (daylight balanced).
Comment by Vince — November 21, 2012 @ 4:11 pm
1. If the aperture + Time + ISO stays constant, the ambient exposure stays constant.(Both = 1/160 @ f/4.5 @ 1600 ISO).
2. Ambient exposure is 2-3 stops under exposed.
3. The top picture looks like direct TTL flash. The green dress is lighter at the top picture than at the bottom. With direct flash you get more light on the background.
4. The bottom picture look more like TTL bounce flash, as the subjects are properly exposed with the light fall-off towards the background. Bounce flash usually gives less light on the background than bounce flash.
Comment by MvH — November 21, 2012 @ 4:16 pm
Different focal length used – the first pic is shot with telephoto as the perpective is compressed and so because of the greater distance to the subject there is proportionally less light fall off than the second pic so the background is more illuminated compared to the subject.
Comment by Steve Garner — November 21, 2012 @ 4:35 pm
One last word from me. The reduced distance between the walk-on softbox and subject explains the more intense light fall-off.
Comment by Allen — November 21, 2012 @ 4:41 pm
Is it the inverse square law? The 2nd photo is taken at an angle where the room has more depth.
Comment by Linda — November 21, 2012 @ 4:43 pm
The second shot has been taken zoomed out. The flash is more dispersed and travels less than the first. So the background is darker.
Comment by LD — November 21, 2012 @ 4:49 pm
The flash head hasn’t been moved on the camera, but because you’ve turned your body, the flash in the 2nd light is not bouncing at quite the right angle to illuminate the rest of the room (hence it’s darker). In the first shot, more of the light is bouncing off the wall over your left shoulder, lighting up the ceiling and other walls.
Comment by Alex — November 21, 2012 @ 4:54 pm
Since a picture is worth a thousand words, I herewith complete my explanation from #128. The ratio A/B is different in both pictures, the square of this ratio produces the difference of exposure between the subject and the background.
Note 1 : The distance from Neil to the bounce surface is the same.
Note 2 : The distance from the subject to Neil is different, hence the different focal length (50mm vs 29mm) to keep the same composition. You can compare the position of the subject in the room by its distance to the lights on the ceiling.
Note 3 : The amount of ambient light is the same and is in fact almost nothing.
Note 4 : The amount of light on the subject is the same. TTL did a good job in both pictures.
Note 5 : The amount of light out of the flash is less in the 2nd picture, hence the dark background.
Note 7 : I may not be right, but at least this story makes sense to me. And I would not understand anything about it if I was not reading Neil’s blog for 2 years, thanks a lot Neil.
Damien
Comment by Damien — November 21, 2012 @ 5:23 pm
Sorry for the previous post, the formatting looked better on my text editor.
Damien
Comment by Damien — November 21, 2012 @ 5:25 pm
Comment by Neil vN — November 21, 2012 @ 5:34 pm
You saved your flash setting prior to shot 1, and it wasn’t right for #2.
Comment by Nick — November 21, 2012 @ 5:40 pm
Front sync verses rear sync?
Comment by Gary S — November 21, 2012 @ 5:55 pm
My guess is your use of the inverse square opportunity. Light dropoff is much less the further away you are from the subject so you moved back from subject and zoomed in to make subject same size.
Comment by Dave Clark — November 21, 2012 @ 6:16 pm
Ok another guess, you had a remote flash setup across the room which fired on the first shot but misfired on the second shot
Comment by Matt — November 21, 2012 @ 6:36 pm
It looks like you had moved so I am thinking that you may have bounced off one of those chandeliers instead of bouncing on the plain ceiling?
Comment by Mamarazzi — November 21, 2012 @ 7:42 pm
Difference between TTL flash output between 2 shots.
Comment by Jaswinder — November 21, 2012 @ 7:45 pm
The subjects appear to be closer to the light source (bounced light off the back wall) so there is more light fall off. A longer focal length won’ make any difference if the light source to subject distance is maintained. Even though the on camera flash may have moved to and fro it still had the power to compensate in order to light up the bounce source and give a correct amount of light. There will be some other factors but main factor is light fall off.
That’s my guess.
Comment by RJ — November 21, 2012 @ 7:52 pm
The biggest different I see here is the the first shot being taken at an angle to the long room and the 2nd shot being taken straight down the long room.
In the first shot. The cameras was at an angle (e.g. 45 degrees with respect to the long room) to the long room and the light from the flash was allowed to hit the side wall at an angle to brighten up the background.
In the 2nd shot, the flash drop-off was much more severe as the shot was taken along (i.e. parallel to the walls of the the long room).
Comment by Wei Tatt Chong — November 21, 2012 @ 8:11 pm
One is ambient metered and the other is metered on the subjects. The two techniques will give you totally different results in regard to the background being lit and and not.
Comment by Gav — November 21, 2012 @ 8:22 pm
The suspense is killing me… and my attempt to simplify the issue at #207 just fell into the abyss.
Comment by Jon Lloyd — November 21, 2012 @ 9:38 pm
All things being equal, the only explanation I can think of is that the surface that the flash bounced off was different. In the first shot the light is diffused throughout the room, so it was most likely off the wall/ceiling. The second shot has the direct flash look so it was probably bounced off a window or mirror.
Comment by Asad — November 21, 2012 @ 9:41 pm
Hi Neil,
In your first photo you were standing further back and using a longer focal length to frame the bride, therefore the bounced flash had further to travel resulting in a reduced amount of light drop off due to the inverse square rule of light and allowing the flash light to mix more with the ambient light.
The second photo was taken closer to the bride using a wider focal length and therefore reducing the distance the bounced light had to travel and increasing the effect of light fall off resulting in a darkened background.
I hope I am right…makes sense to me. :)
Your books, website and this webpage on inverse square law have helped me greatly over the last two years to understand light…thank you…even if I don’t win :)
http://photo.tutsplus.com/articles/lighting-articles/rules-for-perfect-lighting-understanding-the-inverse-square-law/
Comment by Nathan Targett — November 21, 2012 @ 9:47 pm
I would say that you moved your location in the room to take advantage of the ambient light. The darker picture is taken deep into the room, while the lighter one has the wall with lights closer to the right. This took advantage of the lighter closer area rather than the darker depths of the room. I think the key is moving the camera position to have light behind the people. Scott
Comment by Scott Boyer — November 21, 2012 @ 10:29 pm
Sent ItemsWednesday, November 21, 2012 11:53 AM
Hello Neil .In response to your challenge my take is that you walk away from the subject perhaps doubled the distance closer to the back wall ,. Referring to you last articles that would increase light up zone of background and more gradually effect fall of the light . Since you were on TTL mode output of the flash was adjusted automatically .
You are the best teacher and very dedicated to army of confused photographers scared to use Speedlight . I am reading you every post . Thank you again .
Dariusz Adamek
Guelph. Canada . Ontario
Comment by dariusz — November 21, 2012 @ 11:19 pm
There is an ambient light source right at the top of the second photo. In the first photo, that light source is almost completely out of the frame. Since you are using TTL, the flash is automatically compensating for the the brighter light source in the second photo. That’s the difference.
Comment by Brian Lloyd — November 21, 2012 @ 11:33 pm
You used HSS which cut your flash range.
Comment by Ralph — November 21, 2012 @ 11:51 pm
I would say that the lights in the far end of the room were dimmed or turned off.
Comment by Mgarber — November 22, 2012 @ 12:08 am
“Mirror, mirror, on the wall…” Your position changed relative to the mirror, so the bounced light also changed its relationship to the mirror (AKA reflector).
Comment by Kat — November 22, 2012 @ 12:30 am
I am with #274. :)
I think in the first photo, the bounce surface is a normal white-ish wall and the second photo is bounced off the lady in black (you can see here on the right side behind the bridemaids) those girls are talking to.
Comment by Kyle Huang — November 22, 2012 @ 12:31 am
the only difference that I can see is that the first photo was taken from a longer distance with (probably) a tele lens. As a result the relative distances between the girls and the girls and the camera are about the same. The differences are small and so we have a more even light. The same thing is happening also with the bounced light on the walls
Comment by Nikolaos Galanoudis — November 22, 2012 @ 1:31 am
Continuing #197: You flagged the flash in shot 1. The light didn’t spill onto the guests directly, and therefor ttl punched out enough light to bounce forward to illuminate the room and the guests. In shot 2, the flash was not flagged and light was allowed to strike the guests directly, throwing off the ttl metering, producing less than adequate flash to light the room, but enough to illuminate the guests.
Answer?
Comment by Brian Anthony — November 22, 2012 @ 3:50 am
I’ll venture to say that it’s the difference of TTL and manual flash or simply a matter of asking the hall staff to turn up the lights a bit.
Comment by Roger — November 22, 2012 @ 4:05 am
Oh and i also noticed that your position relative to the subject has changed – the first pic there is a lot of hall to cover and the light isn’t strong enough to go that far. In the second pic, it appears you taken a step or 2 left and the other wall is closer and therefore is lit better.
Comment by Roger — November 22, 2012 @ 4:10 am
It’s definitely because the flash light source in the 1st photo is further away than in the 2nd photo. Damien has helpfully illustrated it with his diagram.
Comment by Phil G — November 22, 2012 @ 5:04 am
Seems to be that you are bouncing from some object (e.g. wall) that is behind you/perhaps also to your left. On the first picture you are standing further from it so the flash shoots much stronger in order to properly expose the subjects. That spills the light all over the room. On the second picture you seem to take a step back. Flash shoot is weaker and therefore it does not reach all over the place (just on the left hand side of the chandelier which also blocks some of the light). Also, since you are standing closer to that object, the effective area of the “diffusor” is smaller and therefor light does get spread as widely as in the first case. That’s my guess.
Comment by Nikodem — November 22, 2012 @ 5:49 am
The different is the distance of the main subject to the background. On the first image, the background was much closer to the main subject hence the light from the flash was able to bounce off around the wall. However on the second image, the background is far away from the main subject therefore light fall off very quickly with nothing to bounce of.
Comment by William — November 22, 2012 @ 6:07 am
inverse square law indeed…
the slight difference in distance between you and the subjects means also difference in distance between you and the bounicing surface and therefore difference in distance between the light source and the background.
Comment by mouzhik — November 22, 2012 @ 6:08 am
Hi Neil!
My guess; after the first shot, the bridesmaids walked towards you and your bounced light source.
Here comes Inverse square and ttl: closer the subject to light source = lower power out from flash + greater difference in distance between subject and background = greater light falloff behind properly exposed subject.
Till Monday, Happy Thanksgiving!
Damian
Comment by Damian — November 22, 2012 @ 6:18 am
I think you may have focused on a person further away in the second shot, therefore more power from the TTL flash.
Comment by Rob — November 22, 2012 @ 6:47 am
So if the images were taken within seconds of each other and if the exterior lighting was the same for both, then I think that the difference in lighting between them is due to the FEC. The first shot must be completed with a FEC of around 0, allowing ambient lighting that register, then the second shot the FEC was stopped down to perhaps a value of -1, which made the ambient lighting not register.
Comment by Alfredo Medina — November 22, 2012 @ 7:19 am
My guess is that you exposed for the background, locked that exposure, recomposed and focused on the bride in the first picture. In the second one you simply exposed and focused for the bride and took the shot.
Comment by Gabriel M — November 22, 2012 @ 8:23 am
Further to comment #109
Neil, You’ve created a monster! Can’t stop laughing at the number of people who choose to ignore the help you’ve given. What bit of ‘didn’t change anything’ are they missing?
Not saying I’ve got the right answer but at least I think mine fits the criteria.
And to think you said “the answer isn’t complicated”!!! ;)
Comment by Colin — November 22, 2012 @ 8:50 am
I can see from the images that you moved or at least turned to some degree as there is a change in the perspective and what appears in the background. It looks like in the first image more light has reached the wall on the right hand side than in the second image; by at least two to three stops.
From that I would estimate that for the first image the flash-bounce surface-subject distance was only slightly less than the flash-bounce surface-wall distance; say 90%. As you turned for the second image, the surface that you bounced the flash off of was closer to you. As a result the flash-surface-subject distance was much smaller, say 25-30%, of the flash-surface-wall distance. The actual numbers involved are more or less un-important. The whole inverse square law, light fall off thing would therefore suggest around two-three stops less light hitting the wall in the second shot than in the first.
Here’s hoping I am finally getting the hang of this stuff :oD
Comment by Mark C — November 22, 2012 @ 9:08 am
As you said you didn’t change anything, nor the angle at which the flash was positioned.
Said this, in the first picture the light from the bounce reached a little bit that white wall in the background giving an extra kick of light to the picture; in the second there’ is no such wall and the light is more disperded and gives no help for the background.
Comment by Andrea — November 22, 2012 @ 9:10 am
A simple change in focal length could change the in-camera metering enough to affect TTL.
Comment by Stuart — November 22, 2012 @ 9:31 am
Perhaps, there was a second speedlight set up in the background introducing some additional light.
Comment by Andy — November 22, 2012 @ 9:33 am
It looks to me lke you dialed up the FEC in the first image. Since that setting is on the flash I’m concluding that you’re not calling it a camera setting, since technically it’s a flash setting (correct me if I’m wrong). Otherwise I would say that the flash itself output more light in the first image based on its TTL algorithm.
Comment by Debra Wallace — November 22, 2012 @ 10:08 am
ttl was fooled by camera position being different between the two photos
Comment by Corey Bell — November 22, 2012 @ 10:22 am
Looking at the people and the lines on the ceiling, the first photo was taken at a long focal length, second photo at a wider focal length.
When the subject and background are closer to each other relative to the light source, they will be illuminated more evenly. When the subject and background are farther away from each other, compared to the light source, there will be a bigger difference in illumination. It’s the inverse square law.
That mirror in the background made it seem like the room is longer than it really is. It took me a while to realize what was happening there. Looking forward to seeing what the answer it.
Comment by Mohammed — November 22, 2012 @ 10:26 am
Hi Neil. It looks like you had the subjects move further back and you moved forward, thus moving your front subjects further from the wall behind you (the light source from which you bounced the flash). This ultimately reduced the amount of falloff from the front subjects and the space behind them, since their relative distance from the light source is less, i.e. inverse square law in action.
Comment by mikej — November 22, 2012 @ 10:30 am
I think you expose on the white flowers (which means less flaslight coming out) in the second picture and on the face of the lady in the first picture.
(Sorry for my bad English)
Comment by Annemieke van Baal — November 22, 2012 @ 11:47 am
It is simple as you said at the start.
In shot 1 your bounce surface is further away from the flash (longer end of the room). As you rotated for shot 2 your bounced surface is now much closer to your subjects (side wall)and the fall-off of refllected light is reduced. This is also more obvious due to the additional distance in the background which appears darker.
You can see in image 2 that the reflection of light on their foreheads is much more pronounced indicating a closer more intense light source.
Thanks
Comment by Den — November 22, 2012 @ 1:27 pm
My guess:
Your first shot used bounce flash off a wall in the room behind you some distance away so the TTL flash needed to dump a lot of light to evenly light the main subjects, and this also lit the group behind.
The second shot was bounced off a pillar or possibly the brides white dress and this provided a lot more efficient use of the flash output so TTL calculated you needed a lot less to light the subject, and the rest of the room went dark.
This is probably off the mark but at least I didn’t guess that you had an angel working with you as suggested in one of the replies above
Comment by Stevo — November 22, 2012 @ 3:00 pm
You metered the ttl off different spots one darker than the other
Comment by Chris williams — November 22, 2012 @ 3:12 pm
Comment by Neil vN — November 22, 2012 @ 3:21 pm
I think the difference in the background illumination is due to a change in the flash-to-subject distance. In image 2, Neil moved closer to the subjects — the five women closest to the camera – and zoomed out to a wider focal length to keep the subjects at the same relative size as in image 1. Moving closer to the subjects increased the distance the light had to travel from the flash to the bounce surface behind Neil and then back to the subjects. Although the subjects in image 2 were still within the range of the flash and were properly exposed by TTL, the light falloff beyond them was steeper than image 1 due to the inverse square law. Also, a contributing factor is that image 2 was recomposed to be straight down the hall, whereas image 1 contained more of the right side wall, which was closer and picked up more of the light from the flash.
Comment by Glenn K. — November 22, 2012 @ 4:02 pm
I would say as before, TTL and TTL-BL will give you the same metering for flash on the subject under the focal point (girls) but different background metering, exposure metering is irrelevant as exposure is manual, unless you’re using an SB-700 and you had to use spot metering to force TTL
Comment by Matt — November 22, 2012 @ 5:07 pm
After thinking about this some more I don’t think Neil even moved much if any. The 5 women moved closer to him so he just zoomed out some with a bit of rotation to compensate thus the bounced light didn’t change hardly at all just the amount of flash power required and the angle at which the light hit the 5 women. The simplest answer is probably the right one. Light falloff being the result of the closer subjects.
Comment by RJ — November 22, 2012 @ 5:08 pm
How about, you used the flip- out wide adapter on your flash for the 1st shot and not the 2nd? Or you had the flash zoomed for the 1st shot and not the 2nd?
Comment by Matt — November 22, 2012 @ 5:16 pm
Sorry, I can’t resist another bite – I had an epiphany! This is the bouquet tossing event and the “person in light coloured clothing” I mentioned in one of my earlier posts is none other than the bride, multi-tasking as bouquet tosser and (angelic) reflector! (in the shot with the darker background).
My summary:
Smaller light source than the wall = harsher shadows.
Closer to the subjects = more dramatic fall-off.
Only partial obstruction of the flash = shadow on ceiling.
Comment by Allen — November 22, 2012 @ 5:18 pm
My guess is that your metering area was different. First picture is metered on the background, and the second is metered on one of the ladies.
What also gives a hint is we can see that in that the ladies are a bit over-exposed in the first picture, while they are not in the second picture.
Comment by Robert — November 22, 2012 @ 6:10 pm
Maybe it’s just that the natural light level coming from the windows has changed suddenly due to something like passing clouds.
Comment by Martial — November 22, 2012 @ 7:14 pm
Assuming there is no change in the ambient lighting between exposures, the difference then MUST be something related to the speedlight.
When viewing the two images, the chandeliers on the ceiling appear closer in the top image than they do in the bottom one indicating that a longer focal length was used.
Thanks to what I learned in Neil’s article about the inverse square law (http://neilvn.com/tangents/2012/02/01/bounce-flash-photography-and-inverse-square-law/) I know that because Neil was likely further back from the subjects in the top image using the longer focal length, the distance light traveled from flash to subject increased. This in effect decreased the relative distance between flash to subject and flash to background making the background appear brighter in accordance with the inverse square law.
Comment by Tony Mancuso — November 22, 2012 @ 7:23 pm
Hi Neil
I think in the top picture you simply fired the flash into the space behind you but in the second image it was bounced onto a specific surface – wall, ceiling etc.
Regards
Roy
Comment by Roy Barnes — November 22, 2012 @ 7:24 pm
Hi Neil,
The only variable you have not locked down is the TTL flash.
If everything else is manual or unchanging, the TTL “saw” a different scene for each shot and fired accordingly.
Great blog, keep it up.
Jim
Comment by Jim Schofield — November 22, 2012 @ 8:40 pm
Hello, for me there has to be a second flash, otherwise…
Ruggero
Comment by Ruggero — November 22, 2012 @ 8:46 pm
Comment by Neil vN — November 22, 2012 @ 8:56 pm
The lighter background resulted from the light traveling a much greater distance from the bounce source. Therefore, the background gets about the same amount of light as the ladies.. For the darker background, the ladies are much closer to the bounce wall. The light has a much shorter distance to travel, so the falloff is sudden, and the background receives much less influence from the flash.
Comment by Alan — November 22, 2012 @ 10:09 pm
The focal point was on the boquet lady’s green dress in the first shot, which caused TTL to push out more power in the 1st shot. 2nd shot had the focal point on her skin or the light coloured flowers, which caused TTL to push out less flash power for the 2nd shot
Comment by Matt — November 22, 2012 @ 10:16 pm
Further to 322, TTL metering is center weighted, which means more power is put out if the subject in the centre of the frame is darker
Comment by Matt — November 22, 2012 @ 10:18 pm
Either that, or someone opened a door behind you on the 2nd shot
Comment by Matt — November 22, 2012 @ 10:29 pm
Shot 2 had -1 flash exposure compensation
Comment by Matt — November 22, 2012 @ 11:14 pm
Or shot 1 had +1.0 FEC and shot two had 0 FEC
Comment by Matt — November 22, 2012 @ 11:16 pm
Comment by Neil vN — November 22, 2012 @ 11:29 pm
I’m outta ideas, the only other thing I can think of is that the bounce surface changed somehow, as others have mentioned, i.e. off a wall instead of a mirror, it’s hard to tell without knowing the layout of the room
Comment by Matt — November 22, 2012 @ 11:50 pm
C’mon Neil…
Basically you are just using differing focal length between the 2 shots…
Comment by Sync — November 23, 2012 @ 12:04 am
And no I wouldn’t say the women are as well exposed in the 2nd shot, the dresses look darker and the light falls off quicker for the 2nd shot which seems to indicate that less power was used, and less power was used probably because the close chandelier was in frame, TTL told the flash to bring the power down compared to the 1st shot
Comment by Matt — November 23, 2012 @ 12:14 am
Or is it that the photo contains all women, hence the results are ‘unpredictable’?
:-P
Comment by Matt — November 23, 2012 @ 12:26 am
Second curtain sync
Comment by Paul K — November 23, 2012 @ 12:42 am
Greetings Neil!
Well in the first image you shot the group with the tele end of the lens,also the girls were further towards the wall…
In the second shot they have moved closer to you…the wide angle is a dead give away
and the chandelier is much behind the girls – the inverse square law comes into play…
Indranil
India
Comment by Indranil Choudhury — November 23, 2012 @ 5:07 am
In the first shot, the flash hit the chandelier which spread the light around, in the 2nd, it was only aimed at the ceiling.
Comment by Colin — November 23, 2012 @ 5:57 am
The first one was shot with longer focal length – greater distance between you with the bounced light-source on the ceiling somewhere above you and the subject.
The second image was shot with shorter focal length with a shorter distance between the bounced light-source on the ceiling somewhere above you and the subject.
Same relation between photographer, flash angle, bounced light-source on ceiling.
Just different distances and the flash-TTL takes care of the necessary difference in flash-output.
Comment by Seedeich — November 23, 2012 @ 6:10 am
My guess: somebody passed by and blocked you flash, so it did not bounce properly :D
Comment by Saso — November 23, 2012 @ 6:56 am
I would say that the correct answer was already given by Steve Holmes (reply no.17)……….:)
Comment by Radzio — November 23, 2012 @ 7:54 am
Hello Neil
I believe that for the second picture you took one giant step to your right, then turned and faced the group of girls. In the first picture your flash bounced off the side wall, hit the group and continued onto the other side wall. In the second picture your flash bounced off the back wall, hit the group and nicely diffused away.
I love your blog and use your bounce flash techniques quite often!!
Comment by Patrick — November 23, 2012 @ 10:48 am
” In the second picture your flash bounced off the back wall, hit the group and NICELY diffused away” – actually there’s nothing nice about it… 1′st picture is way better due to nice mix between ambient and flash light…
Comment by Radzio — November 23, 2012 @ 12:17 pm
I would suggest the correct answer was given at no 12 but poorly described. No 17 explained it much better but did not mention what triggered the change in the Inverse square law fall-off. I tried to explain both (your rotation moved your subject to light surface distance) but forgot to specifically mention ‘Inverse square Law’ as the reason for the fall-off. LOL
Comment by Den — November 23, 2012 @ 12:24 pm
Spot Metering vs Matrix Metering
Comment by Alex Keselman — November 23, 2012 @ 1:07 pm
Hi Neil,
Been following your website for a few years now. I’m going to wing it and say something really simple! 1st shot, your flash was fully charged. 2nd shot, exhausted batteries, the flash didn’t fire fully. (Canon user, when the flash fires fully the pilot light is red, when the flash allows you to take a shot without fully recharging the pilot light is green) Probably miles off, but thought I’d have a stab at it! Greetings from Scotland!
Comment by Nigel Low — November 23, 2012 @ 2:32 pm
By altering your position and also slightly zooming are you taking in more of the light from the wall lights, hence under the same camera setting the ambient exposure is increased as opposed to the second shot?
Comment by Scott — November 23, 2012 @ 3:59 pm
Did TTL in the second shot try to compensate for the ceiling light and therefore adjust the exposure?
Comment by Barry Phillips — November 23, 2012 @ 4:05 pm
My guess: in first shot flash power was quite a bit lower (maybe there was a negative FEC – you said you didn’t change camera settings, and nothing about flash settings; or maybe it just randomly underexposed). Exposure is adjusted in postprocessing (again, you said highlight/shadow wasn’t adjusted, but nothing about the exposure). If my guess is right – first shot should have lower SNR/more NR, but it’s impossible to verify without fullsize image.
Comment by valeksensky — November 23, 2012 @ 4:30 pm
The ladies moved and you too. The ambient light was different!
Comment by jer — November 23, 2012 @ 4:57 pm
The difference between the first and second shot is the flash output. The second had the flash power dialed down.
Keeping m’y fingers crossed.
Comment by Alex D — November 23, 2012 @ 5:19 pm
Comment by Neil vN — November 23, 2012 @ 5:31 pm
It appears if the crux may be in the illumination of the ceiling. The ceiling reflects light towards the background.
1. Look at the illumination of the ceiling in both pictures.
Picture at Bottom:
a) The ceiling appears darker above the girls, and towards the right.
b) The left side of the seiling is illuminated, but the people shield the background.
Picture at Top:
a) The ceiling is illuminated above the girls, and towards the back.
b) A lighter ceiling will reflect more light towards the background.
2. TTL flash will expose correctly for the girls.
3. The direction and tilt of the reflected light (bounced flash) varied between the two shots.
4. The light which illuminated the ceiling of the top picture, is responsible for the difference.
Comment by MvH — November 23, 2012 @ 6:16 pm
It looks like the only difference is you used Rear-curtain sync on the first photo and Front-curtain sync for the other. Rear curtain synce captures both subject and background because the flash goes off after the intial exposure.
Comment by Jay Seeley — November 23, 2012 @ 6:20 pm
Comment by Neil vN — November 23, 2012 @ 6:24 pm
The top picture may be direct TTL flash, which also illuminated the ceiling to the right. With direct TTL flash you get more light on the background, and correct exposure of the subject (girls).
The bottom picture may be bounced TTL flash, which resulted in less light on the background and ceiling, but which illuminated the girls correctly.
Comment by MvH — November 23, 2012 @ 6:34 pm
Hey, so I did not want to read everything, but I think the answer is that you changed where you were standing. The background is now the wall, not down the room. Other than that, everything else looks the same. It is simply the perspective.
Comment by Jessica Thompson — November 23, 2012 @ 6:51 pm
To add to my initial response. The rear curtain screen acts like fill flash for the initial exposure.
Comment by Jay Seeley — November 23, 2012 @ 7:00 pm
You moved farther away from your subjects and zoomed in closer. Moving away evened out the light from foreground to background and zooming in kept your subject framed the same way, more or less.
Comment by Peter Salo — November 23, 2012 @ 7:23 pm
Oops! Just noticed comment 261 by Damien so, I guess I’m in agreement with his nifty little diagram. :)
Comment by Peter Salo — November 23, 2012 @ 8:58 pm
I will give it a try: You stated that they are both bounce flash shots. One was bounced off the ceiling and one off the wall.
Comment by Shaie Williams — November 23, 2012 @ 11:44 pm
One more thing, the black thinging was used on one the direct the light further.
Comment by Shaie Williams — November 23, 2012 @ 11:45 pm
My third opinion.
According to the inverse square law, the further our subject+background moves from the light source, the brighter our background will appear, relative to when our subject+background is much closer to the light source, so that the further our subject+background is from our light source, the less dramatic the light fall-off between our subject and background.
In the first picture the background is not that much further from the light source, than the women are from the light source.
In the second picture the women are closer to the light source and therefore light drastically fall-off between them and the background.
Comment by Alfredo Medina — November 24, 2012 @ 6:53 am
I think that comment 355 by Peter Salo is the correct answer!
Comment by Tin Yuen — November 24, 2012 @ 8:43 am
Revised post:
In the first picture, the flash power was dialed down to underexpose the ladies, then in raw the overall exposure was increased, therefore balancing the light with ambiant.
Robert
Comment by Robert — November 24, 2012 @ 9:52 am
Then again,my wife suggests that in the first picture, you just turned the room’s lights on…..
Robert
Comment by Robert — November 24, 2012 @ 9:57 am
During the reception, while you did not re-position or modify your flash or change your exposure, it appears you re-positioned yourself to be more of a right angle to the back wall (possibly a mirrored wall) by rotating to your left, stepping to your right as well as zooming out in the second image. In the first image your bounce flash was not as reflective on the wall/ceiling behind you on to the subject possibly from not being at an optimal angle and/or the surfaces weren’t as reflective (not bouncing on a the reflective surface as close or in an angle that would illuminate the subject as much). This would cause the flash output to be greater on the subject for a proper TTL exposure. This greater output illuminates the whole room more than in the second image where the flash to wall/ceiling bounce flash is at a more optimal angle, distance or bouncing on a more reflective surface so less output is needed for the proper TTL exposure on the subject and does not illuminate the whole room as much as the first. TTL exposure is metered more centrally in the lens so it does not evaluate the whole image during the pre-flash, so images may have different amount of illumination in the background of the subject depending on the intensity of the flash while the central portion of the image is metered more or less correct for the exposure.
Comment by Steve Vequist — November 24, 2012 @ 10:47 am
In the first picture you had your TTL flash mode set to automatic balanced fill flash which adjusts the flash exposure to balance the flash with the exposure of the background. In the second picture your flash was standard TTL which correctly exposes the subject regardless of the background. For some reason I think the second shot is more aesthetically pleasing because there is more pop to the expressions and the background isn’t that interesting. The first image seems to be framed a bit differently to have a more attractive background which is probably why you used the TTL balanced flash.
Sure would love to study with you.
Comment by Dyanne Wilson — November 24, 2012 @ 11:27 am
I am guessing it is a lot simpler than we think. Someone else was taking a picture at the same time which illuminated the room more??
Comment by Jennifer — November 24, 2012 @ 11:56 am
Hi Neil,
My guess is this…
In the first image, your flash was bounced behind you creating a source of light that was further away from your subjects, essentially making the inverse square law work to illuminate the room.
In the second image I suspect that your flash was bounced a bit more upward creating a closer light source resulting in quick light fall off.
Thanks for the fun!
Brian
Comment by Brian — November 24, 2012 @ 12:02 pm
Reading my comment again at no. 230 I should have stated it was the second shot that was possibly simultaneously lit by another photographer’s flash – then the TTL on your flash at that moment reduced power. The first shot was executed as planned.
Comment by Arthur — November 24, 2012 @ 12:35 pm
BFT – Black Foamy Thing
Comment by Dylan — November 24, 2012 @ 1:29 pm
Insufficient flash power for the 2nd picture. The flash was fired before it had a chance to completely refresh its ready state.
Comment by Henry — November 24, 2012 @ 2:08 pm
Hi,
You mentioned that you neither changed camera settings nor flash angle, everything was kept the same – except shooting position, I guess. In the first image the light extends much deeper into the room which means to me that the effective light source is further away than in the second image. My assumption is that the flash was directed behind you (a little to the left and up) bouncing both from the ceiling and a wall behind you. In the first image the wall was far(er) away from your position – in the second image the wall was much closer.
Thanks for the fun,
Jörg
Comment by Jörg — November 24, 2012 @ 3:40 pm
Recycle time?
Comment by julia morgan — November 24, 2012 @ 8:53 pm
The two shots are taken at different orientations, which would result in the light bouncing off a different wall or at a different angle to the wall relative to the photographer and subjects. Using the grid of the ceiling tiles as a reference, the first shot is shooting more diagonally in the room compared to second shot which is shooting parallel to the side walls. The first shot flash appears to travel further before it bounces off a wall, probably bounced more into a far corner or side wall. Even with the same camera settings, TTL will pump the right amount of power into the flash to properly expose the subjects. The rest of the room is a relatively similar distance from an inverse square law perspective and is receives about the same amount of light from the flash. In the second shot, the flash is hitting a wall closer to the photographer/subjects. It is a much shorter distance to the subjects than to other portions of the room, so the light falls off more quickly. Again, TTL will create the correct exposure for the subjects. Had the flash power been set to manual, this would be a very different exercise.
This was a fun exercise, and I confess to still waffling as to whether this is attributed to you moving closer to the bounce wall and changing your focal length.
All the best,
Phil
Comment by Phil Barnett — November 24, 2012 @ 9:41 pm
I am guessing that the ambient light is different in the second than it is in the first. I see in the first shot that the ladies are closer to the chandelier than in the second. So you properly exposed for the ambient light for #1. The ceiling and background in #2 is a lot darker than #1. So if you did not change the exposure to match the ambient light, then you get the bright subjects from the flash and a dark background.
Comment by Michelle Hall — November 24, 2012 @ 11:40 pm
OK, this is a stretch…
To elaborate or be more precise from my first thought at comment #355, you didn’t back up at all. In the darker shot the wall/ceiling was right behind you, therefore the difference in the distance of the subjects in the foreground to the dark background was more than double.
You simply moved to the left and turned a little to the right which in effect, aimed you backward facing flash into a wall/ceiling that was farther away you. Perhaps into the corner. In this way your subjects in front and the background were not effected by the fall-off of light that was no longer happening thanks to the greater distance. (you know, that rule thing… or is it a law?) :)
Comment by Peter Salo — November 25, 2012 @ 1:37 am
Now I’m officially obsessing over this brain-teaser!
Please allow me one last try… This time maybe in the the order the photos were taken.
First shot: Nice, fine, perfect balance of light.
Second shot: “Let’s change the composition and shoot straight down hall and get those chandeliers in the picture” Upon turning to the left the wall/ ceiling is now directly behind you and you get a lot more light now. TTL takes over and in an attempt to give you a good exposure on the girls, reduces the power of the flash.
Result: Since you didn’t change any settings, the foreground exposure is good while the background is now way underexposed.
Solution: Pick one of a few… but I’ll go with, increase the ISO for a good exposure of the room and reduce the flash output on the foreground by dialing down the flash compensation.
OK, I quit now. :)
Comment by Peter Salo — November 25, 2012 @ 2:07 am
different zoom on flash…
Comment by yeller — November 25, 2012 @ 5:20 am
The bounced surface in the first photo was more distant to the subject than the second one.
Comment by Indy — November 25, 2012 @ 10:42 am
I’m not sure if this competition is still open or not – So many people have already answered already. But I’ll have a shot at this anyway.
I would say that the only thing that changed is your speedlights zoom setting.
In the first photograph the flash was set to a wide spread (say 24mm), and the emitted flash spread over a greater area on the wall behind you and reflected further across the ceiling in the room, it becomes a larger light source.
The flash output would have increased in power to properly expose the bride, but it pretty much evenly exposed everyone because it’s such a large light source.
in the second shot the flash was zoomed to a narrow spread (say 105mm). The camera exposed properly for the bride but because the lighting pattern bounced off the wall behind you is a smaller source it did not spread as much and have the opportunity to light the rest of the white ceiling and back wall of the room. The light fall off can be seen to the right side of the chandelier. With a zoomed flash doesn’t have to work so hard to properly expose the metered subject and so will not emit so much power – hence the darker background.
Comment by Randell John — November 25, 2012 @ 12:55 pm
Hi Neil,
Is it that you changed the angle you were facing? So in the first shot you are more angled to the wall on the right so it is getting some of the bounce? In the second shot it is parallel to the bounce so the light runs in the same direction but isn’t spread enough to catch the wall?
Comment by Mark — November 25, 2012 @ 1:34 pm
There are two sources of light on the ceiling in the bottom image which caused TTL to decrease flash output.
Comment by Krzysztof S — November 25, 2012 @ 3:46 pm
Comment by Neil vN — November 25, 2012 @ 3:48 pm
The exposure seems the same on the subjects because you spot metered on the skin and TTL did the rest?
Comment by Peter Salo — November 25, 2012 @ 4:15 pm
Comment by Neil vN — November 25, 2012 @ 4:43 pm
You were closer to your bounce surface on the darker background photo, creating a smaller source of light…?
Comment by Misael Reyes — November 25, 2012 @ 5:00 pm
Neil – this brainteaser has been masterly. It’s 21.00 here in the UK as I write this. Never have I looked forward to a Monday as much in the whole of my working life! You’ve got to do this again one day! Thanks
Comment by Arthur — November 25, 2012 @ 5:04 pm
The difference in the ambient light is due the different distances the light had to travel in each image. The darker image had the light source much closer to the main subject.
(My brain is starting to hurt — btw) :)
Comment by Peter Salo — November 25, 2012 @ 5:26 pm
I might be a tad late, but this has been done by using the inverse-square law :)
Comment by Adamj — November 25, 2012 @ 7:31 pm
Firstly, there is a difference in focal lengths so distance to subject would cause the TTL metering to give a higher flash output on the first.
Secondly, the camera position has changed bringing the side wall into effect on the first.
and
Lastly, you standing at eye level on the first while kneeling on the second changing the angle of your light source in relation to your bounce surface.
Due to the hotspot on the ceiling in the second image and the look of the light in both images. I would guess your flash was angled towards the subjects and a bounce card of some sort was employed.
Comment by Charles Ostrand — November 25, 2012 @ 10:19 pm
Tear in the space–time continuum
Comment by Matt — November 25, 2012 @ 10:25 pm
After all of the discussion (mine included) regarding the difference in the distance of the light source, i.e., from on-camera flash to wall/ceiling, to subjects in the distance…
It seems that the evenness of the light was achieved by reducing the “gradient of light fall-off” by increasing the distance of the subject and the background from the light source.
So, I will quote from a trusted source, “The Inverse Square Law implies that the further our subject+background is from our light source, the less dramatic the light fall-off between our subject and background.”
If ya don’t believe me click here:
http://neilvn.com/tangents/2012/02/01/bounce-flash-photography-and-inverse-square-law/
Comment by Peter Salo — November 25, 2012 @ 10:58 pm
OK fine…
Someone turned up the brightness of the chandeliers! :p
Comment by Peter Salo — November 25, 2012 @ 11:14 pm
… and the wall sconces too!
Comment by Peter Salo — November 25, 2012 @ 11:21 pm
Hi Neil! For me it´s because You have changed Your position and the bounced flash illuminated this “new” background in the 1st photo. Thanks!
Comment by Artur Ocubaro — November 25, 2012 @ 11:49 pm
Hi Neil
As YOU changed your position with the subject, the TTL mode has changed.
As a result, the TTL flash exposure was adjusted accordingly via the camera and not YOU. Hence TTL.
Angelo
Australia
Comment by Angelo — November 26, 2012 @ 12:34 am
Hi Neil,
I’d have to say after the first shot you reduced the distance significantly between the bounce surface and the subjects, likely by shooting behind yourself in the first shot, and vertically or slightly in front of yourself in the second shot.
Comment by Terry — November 26, 2012 @ 3:55 am
Disclaimer: I do some nightlife photography and balancing flash with distance to subject (in addition to ambient by dragging the shutter) is something I constantly think about.
TTL meters using a combination of factors in addition to ambient light, one of which can be distance to the subject and focal length. In the first image you’re further away with a longer focal length leading to an increase in flash output. In the second image you’re closer with a shorter focal length. This leads the metering system to decrease flash output to correctly expose the subject.
The subjects are correctly exposed, but what about that ambient?
Flash output decreases exponentially over distance, so a light source that correctly exposes something 1′ away would mean something 2′ away is getting 1/4 the light, or a two stop underexposure. Let’s throw some numbers at your examples and see how it plays out. (Note: I haven’t built a model to measure distance based on guesstimated sizes of objects related to focal length, these are just really rough estimates). Assume you’re 20′ away from the subject in your first photo. The TTL system kicks in and fires the flash for a correct exposure 20′ away. That means that something 40′ away is two stops under. Not bad! The ambient is still there. Now step way in and take the second picture from 8′ way. Suddenly that wall that’s 40′ in the background is getting a -6 stop exposure. Much darker than the earlier image.
More ambient is gained by a being further from the subject (either you or the light source) and a higher flash power to decrease the light falloff. Of course you could also just drag your shutter down to 1/20th or 1/10th if you’re not too worried about the background or shooting in a situation that’s vastly underlit (think most clubs and bars).
Interesting brainteaser, I hope you do more.
Comment by Joshua Kehn — November 26, 2012 @ 4:26 am
As you change position, the light from the chandelier are affecting the camera metering,hence affecting the output of the flash.
Comment by cs chong — November 26, 2012 @ 6:09 am
Not sure if this is still open, but will have a punt anyway :-)
Looks to me like there are two things changed in the second shot:
1) zoom – the far background is further away so you’r closer to the subject
2) angle relative to the subject, you’re looking down the room for the second shot
The second point results in a different amount of light being emitted by the chandeliers most likely affecting the TTL balance for the flash as they’re more prominent in the second shot.
I also know that you like bouncing behind you and usually to one side, judging by the shadows slightly to the right in these shots but difficult to say. So if there’s a wall behind you in the second shot you’re going to get more bounce flash direct on the subject.
So I think in the second shot, you’re getting more direct bounce from a wall behind you and the TTL is over compensating for the additional lighting in the room resulting in a more exposed subject and less exposed background, that’s also slightly exaggerated by being slightly closer to the subject.
Comment by Pete R — November 26, 2012 @ 7:18 am
The first uses second curtain sync, the second shot uses first curtain sync?
Thanks for helping us learn how to shoot better…
Comment by Fred Hogrefe — November 26, 2012 @ 8:01 am
Seems the chandeliers are installed in a concave part of a ceiling. This is where you bounced your flash on the second photo that is why the light didn’t spread much to the rest of the room; it came down in a circular way, more directional, like a softbox umbrella.
The first photo simply had more light because you bounced the light from your flash directly on the flat ceiling (or maybe a wall), hence the light spread more evenly.
I do wish to show you some of my work from an event and be honored to have some critique!
Thanks for the brain teaser!
Comment by Alaric Yanos — November 26, 2012 @ 8:36 am
You say you didn’t adjust the highlight/shadow sliders, but since it’s not the ambient and nothing’s changed with the flash head position or modifier, I’m inclined to believe this:
In the first shot, the flash TTL prefire was able to hit the wall behind the women, thus allowing it to give a partial meter such as 1/2 or 1/4 or even less because the TTL system was satisfied with less light, and it therefore appears that there is a good mix between ambient/flash. This shot may have been slightly underexposed (with regards to subject).
The second shot has a lot more depth to the background, thus the TTL saw blackness and fired at max power. This shot may have been slightly overexposed (with regards to subject).
When bringing the shots back to normal exposure (and making them look similar), one appears to have more ambient and one appears to have less because the initial subject exposures were incorrect.
You said these were edited, and you didn’t say the exposure was unmodified, so that’s my new guess.
Comment by Josh Ellis — November 26, 2012 @ 9:30 am
Im going to say you TTL zoomed the flash differently in the two pics?
Comment by Ayaz Sayeed — November 26, 2012 @ 12:10 pm
Your camera and flash were farther from your subject and background in the image with the brighter background, allowing the background to appear lighter due to the Inverse Square Law. Great lesson, got it!
Comment by Nadia — November 26, 2012 @ 2:08 pm