October 3, 2010

photography questions & answers

I started the initial numbering of this serial topic with three digits. And since I thought of this being a monthly post, it would seem like we’re in for the long haul here if we’re ever going to reach the hundreds. So, continuing with this post where I check recent search engine queries, and answer a selection of 10 questions more directly …

01)  increasing flash will eliminate ambient light

It doesn’t quite work the way as stated there. If you have correct exposure for ambient light, then adding (correctly metered) flash to this, will just over-expose the photograph. To eliminate or reduce the ambient light, you first under-expose your available light to a certain extent, and then add flash to give you correct exposure. Now you can progressively eliminate the ambient light by changing your settings, but keep your flash exposure such that you get correct exposure.

You would change your shutter speed first to reduce the ambient light, but usually not higher than maximum flash sync speed. Then you need to juggle the aperture and ISO settings … and add flash to this. This is the usual technique when your available light is ugly. Think of tungsten lights in the ceiling, directly overhead.

This question then neatly segues into the next question and answer …

02)  what is the higher shutter speed to eliminate ambient light?

It’s not so much the higher shutter speed specifically, but a combination of your settings – aperture, ISO and shutter speed. By the time you under-expose by 5 stops, you’re not going to see much ambient light register. You could therefore eliminate your ambient light by changing to a small aperture and low ISO when you work in light levels that aren’t super bright.

Why 5 stops? Consider that changing your settings by a stop, double or halves the amount of light hitting the sensor (or film). Then, if you consider 18% as the middle tone .. then one stop down is 9% .. another stop down is 4.5% … another stop down is about 2% … another stop down is 1% … and another (the fifth stop down), isn’t much light at all.

03)  why is my bounce flash creating a shadow?

… because you insist on bouncing your flash forward at 45 or 60 degrees, or using a piece of plastic on your speedlight when you’re shooting indoors. More careful consideration of what you want to achieve with your light, is essential here.

04)  recommended aperture within situation

Your choice of aperture is usually dictated by the depth-of-field you need, whether shallow or deep. Anyone who isn’t familiar with depth-of-field and how aperture affects it, needs to stop being so lazy, and get a good basic book on photography and do some homework, such as Bryan Peterson’s book on Understanding Exposure. This stuff is one of the most essential basics in understanding photographic technique.

05)  is there a problem having two catch-lights?

You know what? It doesn’t bother me. I am sure the more classical portraitist will have a conniption at this, but it really doesn’t bother me. I know, heresy!

06)  how do you disable TTL flash?

Well, not so much in the way of disabling TTL flash, but the opposite of TTL (and Auto) flash is manual flash. With TTL flash, the camera and flash controls the flash’s output (with you nudging it either way with Flash Exposure Compensation). With manual flash, the output is constant.

07)  TTL flash is not accurate when photographing darker people

… and I have to add that neither will it be accurate when photographing pale people in light colored clothes. TTL flash, and any other automatic mode of your camera, is dependent on your camera’s metering system … which tries to evaluate the scene & subject as seen through the lens. Therefore the camera (in this case with TTL flash) will be dependent on the tonality of the subject / scene.

Your camera is always trying to expose for the subject / scene as a mid-tone, and whenever the subject / scene is darker than average, your camera will over-expose (trying to expose for the darker subject / scene as if it is a middle tone. You need to interpret your camera’s metering display, and adjust accordingly. My recommendation will always be to shoot in manual metering mode. Then you have control.

08)  why can’t I use aperture priority with flash

Well, you could use aperture priority with flash, if / when:
- you make sure you stay at or below maximum sync speed, or
- you set your camera & flash to high-speed flash sync, and know that your flash output will be considerably reduced when you do go into HSS mode.

One of the cries for help I often see, is a photographer saying they get great available light exposures, but the moment they switch their flash on, they get over-exposed photographs. The reason for this is that they are using Aperture Priority, and getting settings like 1/1000 @ f4 .. but the moment they switch the flash on (without HSS enabled), the camera limits the shutter speed to maximum sync speed .. and they get over-exposure.

09)  bring detail back in bride’s dress with actions

The actual query was about a specific action set. However, the answer remains the same. If you need to show detail in a bride’s dress – and generally you should – then the first place to start with this is in the lighting and positioning of the bride. Fixing blown-out areas is a second option … and for this, you have to work with the RAW file. You absolutely have to shoot in RAW anyway when photographing weddings. (And nearly any other situation I can think of.)

Back to the specific question – if you need to bring detail back in a JPG, then you have clear indication you need to adjust your lighting technique AND shoot in RAW. Always RAW. JPG is not an option if you photograph weddings. Fixing the JPG with an action in Photoshop already means you’re in a dead-end street.

As the final one for today is an oddity again:

what planet was first discovered by photographic methods?

apparently, planet neil!

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{ 12 comments. } Add a Comment

1 Stephen October 3, 2010 at 7:20 pm

Haha. That last query is a winner! :-)

Thanks for your link on Understanding Exposure. I didn’t realize it is in the third edition. I need to pick it up to go along with your book.

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2 Jorge October 4, 2010 at 12:11 am

Hello Neil, I’m trying to use ttl flash like you suggest. But it is acting like manual flash. I mean I am getting too much power even with low iso.

You say ttl is supposed to work toguether with the camera. I have a 530ex ii but ettl does work.

And if you can can you please write about function 05-3

thanks

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3 Neil vN October 4, 2010 at 12:19 am

Jorge .. there could be a few causes for your problem.

I suspect the most likely cause of the problem is one of range. You’re simply too close to your subject for your chosen distance. Especially if you’re using direct flash, you could be too close for the camera to react in time to cut the light from the flash. Check the distance scale on the back of your flash if you’re using direct flash, to see what the range is.

Alternately, you might have your FEC set to a positive value, thereby always blowing out exposures.

Then there is also the (small) chance that your flash or camera is faulty.

I don’t have the 530EX, so I don’t know the custom functions. Sorry.

Neil vN

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4 Jorge October 4, 2010 at 12:31 am

Thanks you! I do appreciate hopefully you come to Chicago this coming year.

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5 Anil Fernandes October 4, 2010 at 5:40 pm

Hello Neil,
I usually shoot potraits and weddings and try to implement the bounce techniques that you have discussed in your articles. It works well for me almost everytime and am quite happy with the learnings that i had so far from your articles. However, when i bounce flash or flag it, I see that I dont get good catch lights. the catchlights are very weak and are not sharp and definite in shape..
Am i doing something wrong or my way of bouncing flash is incorrect?

Reply

6 Neil vN October 4, 2010 at 5:49 pm

Anil … it is most likely to do with your angle that you bounce your flash. I suspect you’re still bouncing your flash too high up. (Difficult to guess without a sample photograph.)

For me, when I shoot indoors, even in fairly large rooms, the catch-light in the eyes are there nearly predictably so. Follow the links in that article. There are more examples and discussion of the technique.

Neil vN

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7 John Olszewski October 4, 2010 at 7:03 pm

This post was funny and great! The reason why it was great was because I just faced the issue you mentioned above on this page “increasing flash will eliminate ambient light” when I was at a party yesterday.

When I got home and looked at my pictures, my efforts on the scene to get rid of the ugly florescent overhead lights while shooting with flash just didn’t work well enough. There’s an ugly greenish tint everywhere.

I thought to myself, “Let me jump over to Neil’s web site and see if there’s anything about this”. And coincidentally, it was on the front page!

I tried what you mentioned above and it worked perfectly when I just tested it in my house.

Another tip of the cap to you!

John

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8 Stephen October 4, 2010 at 11:51 pm

Neil,
In your response to Anil, your link for “the catch-light in the eyes are there nearly predictably so” points directly to an image. Were you trying to point Anil to one of your blog articles?

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9 Neil vN October 4, 2010 at 11:56 pm

Thanks! I’ve fixed the link now.

Neil vN

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10 Arun (tokyo) October 14, 2010 at 4:54 am

Hi Neil,
May be you might answer this question in one of your next post. But I was just wondering about this for a while and checked the web and didnt get a definitive answer.
Does the Auto Focus speed depend on the camera body on the lenses with built in focusing motor?
Thanks
Arun.

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11 Neil vN October 14, 2010 at 5:48 pm

Arun, in my experience the camera makes a difference even with lenses that have built-in motors.

As an example, even though the Nikon D3 and Nikon D700 have the same AF module: Nikon Multi-CAM 3500FX autofocus module

.. the D3 does drive the lenses faster in my experience.
I would be surprised if this wasn’t common-place with other manufacturers as well, where the beefier cameras drive the lenses faster.

This of course is just an anecdotal observation and not borne out with actual field tests of lab tests.

Neil vN

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12 Arun (tokyo) October 14, 2010 at 9:45 pm

Hi Neil,
Thanks for sharing your observation. The reason I posted the question was, I am in the market to buy the nikon 70-200mm f2.8 for my D90. (My current 18-200 struggles to focus in telephoto on many occasions and I miss many moments of my kids). So I was under the impression that 70-200 might be able to over come this because it might have a better built in motor. Also the fact that has wider aperture throughout the focal lenght unlike 18-200 which is a f5.6 at telephoto. And I thought smaller aperture would have impact on focusing in low light conditions.

Well focusing speed is not the only criteria for me to buy it, it is the sharpness and the bokeh you always praise about this lens, but just wanted to get an opinion.

This is the best blog on photography so far I have found on the web. I am glad that I bumped into this long ago, which gave me the courage to shoot in manual mode. (Also teach me not use manual for flash and rather use TTL) And this perfectly suits my situation of taking pics of my kids. I am comfortably settled in this techinique for more than a year now!

Thanks again for all your time and efforts helping novices like me.

Arun.

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