August 2, 2010

high-speed flash sync / auto FP .. vs .. normal flash

There have been a number of questions about high-speed flash sync (HSS), and how it affects the output from your flash.  There were also some questions asked about high-speed flash sync with this recent post where we tried to reverse-engineer a photo.

I decided to do a series of comparison photos, so we can actually see what happens before, at and beyond maximum flash sync speed.  And we can also see what happens with high-speed flash sync. To do this, I set up very simple portrait lighting using a single speedlight and a large umbrella.  A simple white paper-roll backdrop, and our model, Rachel. Here is the setup in my dining room …

The large (60″) umbrella to my left, and a small reflector to the right to add a little bit of fill.  Ideally the reflector should be larger and closer – but this isn’t so much a portrait session as it is about photographing sequences of images at various shutter speeds.  I stayed close to the umbrella – keeping it as close to the lens’ axis as possible – so that the light is as even as we could manage with a single speedlight setup.  Of course, the reason for it only being one speedlight is that we can now observe its behavior.

For all the images in this article, the speedlight was set to give full output in manual mode.  This way we aren’t bringing in the uncertainties of TTL flash.  TTL flash is an automatic metering mode, and there will be variations in output if we change our composition.  Manual flash is consistent and predictable.  I worked at full output so that we can more clearly see some of the effect of going to high-speed flash sync.

Initially, I triggered the flashgun / speedlight with radio transmitters.  PocketWizard Plus II units, to be exact.  They don’t allow high-speed flash sync.  So we can now see what will happen then.  For the final sequences where we go to high-speed sync (HSS), I used an on-camera speedlight as a Master, to fire the Slaved speedlight mounted with the umbrella.  The Master’s output was disabled, so we’re just dealing with one speedlight’s effect.

In the spirit of keeping much of the info on this site system-agnostic, we’ll look at how the Nikon D3 and the Canon 5D works.

 

how does the camera’s shutter work?

Before we get deeper into this, we need to cover some basics first – how the camera’s shutter works. The focal plane shutter found in D-SLRs, consist of two curtains that open and close.  They open and close with a certain timing, to open the sensor / frame to light.  When the shutter is tripped, the first curtain opens, revealing the sensor (or frame) to the light, and then the second curtain closes.  The time interval between the first curtain opening, and the second curtain closing, is the shutter speed.  It can be 1 second, or it can be 1/60 of a second, or as short as 1/4000 of a second.

Looking at the top part of the diagram, we can see the timing of the flash pulse. With normal flash sync (shown here as Low Speed flash sync), the flash is a near-instantaneous burst of light.  (Around 1/2000 of a second, although this varies on the design of the flashgun, and how the flash pulse is controlled.)  For description here, let’s just regard the flash burst as instantaneous.  Therefore we need the entire frame open so that the entire scene / subject is revealed by the light from the flash.  Otherwise, part of the scene / subject will be obscured by one of the shutter curtains.  (We’ll see this in another sequence of images here.)

There will be some shutter speed which will be the highest shutter speed at which the first curtain has just stopped moving, and the 2nd curtain has not moved yet.  One notch of a shutter speed over this, and you will have part of one of the shutter curtains obscuring the sensor / frame.  (More about maximum flash sync speed here.  It is one of the essential things we need to know about, and understand, when we deal with flash photography.)

With high-speed flash sync – a truly amazing bit of engineering – the flash’s output is released as a rapid series of light pulses.  The flash is now effectively continuous light over a very short duration.  Now, when we go over maximum flash sync speed, the flash is released as that short period of continuous light, and we can take our shutter speed much higher than maximum flash sync speed.

This change from a high-energy near-instantaneous burst of light (normal flash), to the short period of continuous light (high-speed flash sync), does imply a loss of effective power.  It makes sense in that a lot of the light from our flash will just hit the shutter curtains, and won’t hit the actual sensor.  In other words, much of the output from the flash in high-speed flash sync mode will be lost.

And this is where the rest of this article comes in …

 

 

maximum flash sync speed

So let’s look at how the flash output appear using old school radio slaves which don’t allow us to go to high-speed flash sync.  This is how studio-type shoots are usually set up .. various flashes and light modifiers set up, and balanced .. and then tripped by radio slaves.  Normal flash sync.  In other words, no high-speed flash sync.

Here is the first sequence, using the Nikon D3.  The next sequence is with the Canon 5D.  I wanted to show that the behavior of normal flash sync  and maximum flash sync speed is universal for all focal plane shutters found on D-SLRs.

The Nikon D3 (like most of the bigger Nikon D-SLRs) have a maximum flash sync speed of 1/250th. Below that, and if there is not much ambient light, the choice of shutter speed has NO effect on the flash.  We just need the entire sensor / frame to be open to the blitz of flash.  This can be at 1/8 or 1/60 or 1/125 … as long as it is at, or slower than maximum flash sync speed.

However, as we can see there, at 1/250 we start to see the edge of the one shutter curtain.  This is due to propagation delay.  (More about this in a short while.)

Here is the same sequence for the Canon 5D.  The 5D has a maximum flash sync speed of 1/200 and we see the same effect with the higher shutter speeds obscuring the flash exposure.

btw, if for some reason you want to see slightly larger versions of those, click on the two sets of images for the larger side-by-side version.

 

propagation delay of the flash trigger signal

As you could see there with the sequence of images for the Nikon D3 and the Canon 5D – even though you might be working at maximum flash sync speed – you might still get the edge of a shutter curtain.  This is due to something called ‘propagation delay’.

For these images we were using radio transceivers to trip the flash.  (Pocket Wizard Plus II units.)  As mentioned earlier, they are simple devices that just trigger the speedlights.  There is no intelligence there between the camera and speedlights.

So this is where slight synchronization errors can creep in.  Where we are working right now at maximum flash sync speed, we’re on the very edge of any specific camera’s capabilities.  So when we trip the shutter, the camera has to fire the transmitter mounted on it; which then trips the receiver connected to the speedlights / flashes; which in turn fires those speedlights / flashes.  There is a whole chain of events that take place within finite time.  And that is where any slight synchronization error will show up … just like it does here with the edge of the shutter curtain showing.

This is a common-place occurrence, and not just inherent to the two cameras I used here.  Any studio shooter will have experienced this problem and will know to use a shutter speed lower than maximum flash sync speed when shooting in the studio.  A shutter speed like 1/125 or 1/100 or 1/60 is fine when working in the studio where ambient light levels are low.  The shutter speed has no effect then on the flash output, so any shutter speed lower than maximum flash sync speed is fine in the studio.

On-location though, I do use maximum flash sync speed, even if there is the chance of propagation delay.  The reality of on-location photography is that we are much much less likely to see the effect of flash exposure at the edge of the frame.  For example, I mainly do portrait photography on location.  My subjects are usually more centrally placed.  Hence, propagation delay doesn’t affect me.  I shoot at maximum flash sync speed to get the most efficiency from my flash.

 

video tutorials to help you with flash photography

If you like learning by seeing best, then these video tutorials will help you with understanding flash photography techniques and concepts. While not quite hands-on, this is as close as we can get to personal instruction. Check them these and other video tutorials and online photography workshops.


 

high-speed flash sync (HSS) / auto FP

Okay, finally we get here.  Let’s see what happens when we go past maximum flash sync speed, with HSS enabled.

Here is what the Nikons do:
(Actually, this is what pretty much every camera does that has HSS capability.)

Here is what the Canon 5D does.  Very similar to the Nikon D3, with a slight quirk around the point we get to maximum flash sync speed.

The Canon 5D, and the Canon 5D mark II, both have the same quirk at maximum flash sync speed.  If you are at max flash sync (1/200), with or without HSS, the output is affected differently.  This is something I mentioned in an earlier post on maximum flash sync speed.  It is just something to be aware of with the 5D bodies.

So let’s look at the implication of those two sequences of images.

The moment we go over maximum flash sync speed, our output from our flash drops considerably.  It makes sense:

If we are in normal flash mode, then the flash is an instantaneous burst of light.  We just need our entire frame / sensor to be open, for flash exposure to be consistent from edge to edge.

The moment we go into HSS mode, then the flash output is essentially continuous light. And … continuous light is affected by shutter speed choice.  Think of ambient light. If we change our shutter speed, we change our exposure.  This is exactly what happens with flash in HSS mode.

 

linear response of High-Speed Flash Sync

As mentioned, since HSS flash acts like continuous light, it should have a similar linear response  So let’s see what happens when we change the aperture in relation to the change in shutter speed.

And there is the linear response, clearly to be seen.

1/500 @ f4  … 1/1000 @ f2.8 … 1/2000 @ f2

This is also obvious then why we need to be at maximum flash sync speed when working in bright light and trying to overpower the sun with flash.  (At, or just below, maximum flash sync speed.)

For these examples, we had 1/250 @ f11 … which would, for ambient light only, translate to 1/2000 @ f4 as an example.  Yet, here we have an equivalent of 1/2000 @ f2 when going to HSS.

According to the examples here, we lose about 2 stops in comparison, if we were considering ambient light.  eg, going from 1/250 @ f11 to 1/500 @ f4

Now, when we go even higher, the linearity starts to flatten out.  Instead of 1/4000 @ f1.4 it would appear that we lose about 1 third of a stop of light, and have to open up by dropping the shutter speed slightly to 1/3200 to get the same brightness.  But this could also be partly due to working at wide open aperture on this lens.

Let’s see if the same linearity exists for the Canon 5D:

Indeed, there it is:

.. with the same tapering off in the linearity when we go super-high on our shutter speed.  I had to open the shutter speed by a third of a stop to get the same exposure again.  Although, similarly, this might be partially due to working at full aperture on the Canon 85mm f1.8

 

the implications of High-Speed Flash Sync

So the output drops considerably in HSS mode. This implies several things:

1.  When we work in bright ambient light, then we have a sweet spot at (or just below) maximum flash sync speed, if we want the most efficiency from our flash.  This is because the higher shutter speed implies a wider aperture .. and this wider aperture allows our flash to reach further, or work less hard for the same exposure.

2. If we want correct flash exposure with HSS flash, then we need to move our flash much closer to our subject if we are using flash as the dominant source of light.  Or we need to be aware that our flash will be merely fill light, since the output is affected dramatically.

3. If we want to control our depth-of-field, we are much better off using neutral density filters, than going to HSS mode.

4.  You can’t “overpower the sun” by going to HSS.  If anything, you should not be in HSS when you are dealing with bright light.  You need to do something entirely different to overpower the sun with flash.  This idea that you go to a much higher shutter speed to control the available light when you use flash, is one of the biggest fallacies I’ve come across on the various photography forums.  It simply does NOT work that way.  The next section will show exactly why.

5.  Because of the loss of effective power with HSS, you need to double up, or quadruple up on speedlights to compensate if you are shooting in bright light.  Alternately, you can move the flashgun much closer, and use direct off-camera flash, as with this photograph.  This is Aleona, one of our models at the flash photography workshops, leaping into the air. I wanted to completely freeze any movement, and went to a high shutter speed.

settings:  1/2000 @ f3.2 @ 400 ISO;
Manual flash at full power from an off-camera Slaved speedlight,
controlled wirelessly  with the on-camera flash set to Master.

 

high-Speed Flash Sync – the final word

Hopefully this article will help illustrate what happens with high-speed flash sync. What I wanted to show here is that there is something very specific happening, and that it is predictable. When we are aware of what is happening, we can work with it, or around it, with a clearer understanding. Once we understand what is happening with our equipment and the technology we are using, then it becomes much easier to do what we really want to do … create inspiring photographs!

 

recommended neutral density filters

 

 

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{ 62 comments. } Add a Comment

1 Thorsten August 2, 2010 at 6:46 pm

Thanks for putting this together Neil. A lot of effort went into this and I think it’s worth reading more than once to get the full benefit of it.

You mentioned that “Initially, I triggered the speedlight mounted with the umbrella, with radio transmitters. PocketWizard Plus II units, to be exact. They don’t allow high-speed flash sync.” I’ve always thought this way too about the high-speed flash sync ability of the PW Plus II units but then I came across an blog article by Damien Lovegrove (http://www.prophotonut.com/2010/05/23/18000th-flash-sync-with-broncolor-mobil-and-canon-5d-mk2/) and since then I’ve been trying to get my head around what exactly is going on here. I’m still no wiser, but still keen to understand more about what can and can’t be done with current technology, so I’m always interested in reading posts like this.

Thanks,

Thorsten.

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2 Neil vN August 2, 2010 at 6:56 pm

Thorsten, it is similar to what I explained here in using the Quantums at higher than maximum sync speed, and using the slower decay of the signal when shooting at full power.

Neil vN

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3 Tomasz Kwolek August 2, 2010 at 7:00 pm

so, Neil, let me ask.. even if I use the cheapest wireless triggers like “made in china” with no-ttl, only manual, BUT i have got dedicated flash with HSS.. so then.. am I able to reach highest shutter speeds for example 1/500 ? I mean: it depens only of flash? or it depends of triggers too?

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4 Neil vN August 2, 2010 at 7:05 pm

You only get HSS if you use the camera and flash’s actual technology, whether:

1. your dedicated flash remains in the camera’s hotshoe,
2. you use the camera and flash’s wireless system.
3. you use appropriate wireless triggers such as the Radio Poppers that utilize the wireless system of your camera.

So in your case, you’re out of luck with the made-in-China triggers.

Neil vN

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5 Brian Carey August 2, 2010 at 7:09 pm

Thanks for the detail Neil, this sure took a lot of work! I got a small piece here if you get a chance please have a look, http://blog.briancareyphotography.com/2010/07/high-speed-sync.html

@Thornsten, I’ve seen similar things done by using a connected flash to obtain high speed strobes from a monolight but not a pocket wizard. Interesting stuff!

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6 Stephen August 2, 2010 at 7:13 pm

If it helps anybody, I pulled this from Wikipedia:
“Modern lenses use a standard f-stop scale, which is an approximately geometric sequence of numbers that corresponds to the sequence of the powers of the square root of 2: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128″

So, from f/11 to f/4 is a drop of 3 full stops.

This is the only way for me to keep track of full stops.

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7 imanayAieR August 2, 2010 at 7:33 pm

hi, have u given Alpha system flash a try?

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8 Neil vN August 3, 2010 at 12:24 am

Unfortunately I can only afford so many cameras to play with. : )
I wouldn’t mind having a top-end Sony D-SLR though.

That said, I would be hugely surprised if the Sony cameras … and Pentax and Olympus … didn’t follow the same observations here. There is a definite physical and mechanical mechanism at work here. It is predictable.

Neil vN

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9 Peter Buitelaar August 3, 2010 at 5:35 am

Dear Neil,
A very good, clear and good understandable explanation. I like to use large apertures for portraits thus HSS is an interesting option in some cases but it is clear that it can be tricky too.
I’m a fan of your website and from some of the tutorials I make a PDF file directly from your website. I don’t know if you will place tutorials in your new book otherwise it is maybe an idea to place Tutorials as a PDF directly as a download on your website.
Kind regards,
Peter

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10 Eric Langlois August 3, 2010 at 10:22 am

You rock! This analysis is dead-on exactly what I needed to read as I tinker on the edge of HSS to attempt to over power the sun with less flash while using a wider aperture. I’ll stick to my higher powered flashes and ND filters for now. Thanks again Neil!

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11 Gene Lobb August 3, 2010 at 1:36 pm

I had read somewhere that regular flash can sync at much higher speeds if you have an electronic shutter. I tried this with my old point & shoot and a slaved flash and seemed to do fine until about 1/800 of a sec shutter speed. This was a cheap camera, but maybe you could go higher with something more recent, or on camera, and more sophisticated.

I guess what I am trying to say is keep HSS for fill flash at higher shutter speeds but if you really want to use max sync for the power, why not buy a good camera with an electronic shutter?

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12 Michael Ty August 3, 2010 at 3:02 pm

Hi Neil. Thank you for the informative article and testing. Good thing your smoke alarm didn’t activate. :)

Can you shed light on the 1/320 non-HSS mode of the Nikon D300? How does it work without HSS?

Also, I tried some experiments on sync speed with a YongNuo YN-560 flash and found the results hard to explain.

Here’s the baseline shot at the sync speed, with the flash on-camera (sorry, my flash is stuck at zoomed mode).
D300 @ f/32, 1/250:
http://lh4.ggpht.com/_njEpHb-ltxI/TFUlW_G3y9I/AAAAAAAAPos/vaeYJoA6Zuo/s288/_DSC9590.JPG

At 1/320, there is no visible rear curtain, and only a slight reduction in power:
D300 @ f/32, 1/320 (off-camera):
http://lh6.ggpht.com/_njEpHb-ltxI/TFUlex11JNI/AAAAAAAAPow/Qlk7SqrZfFc/s288/_DSC9592.JPG

Even in optical slave mode, I’m still able to sync at 1/320:
D300 @ f/32, 1/320 (off-camera):
http://lh4.ggpht.com/_njEpHb-ltxI/TFUlnC3mB1I/AAAAAAAAPo4/eBmdYq-cB78/s288/_DSC9597.JPG

(Fwiw additional testing info here: http://betterfamilyphotos.blogspot.com/2010/08/yongnuo-yn-560-flash-update.html )

Thank you very much in advance.

Best regards,
Michael

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13 Neil vN August 3, 2010 at 4:03 pm
14 Rijn August 3, 2010 at 4:13 pm

Hi Neil,

Just found your website by accident and your explanation of how HSS works and why you need to use the max sync speed for best effects is just SO clear. Much of this stuff I kind of figured out myself, but this provides me the knowledge to know what I’m doing and not relying on trusting things will work out well. Thanks for that!

Please keep us posted via the monthly newsletter when you’re planning to come over to Europe (Netherlands) for a workshop.

Best regards,
-Rijn

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15 Matt Heath August 3, 2010 at 4:23 pm

Excellent post once again. I’m eagerly awaiting your your posts on balancing flash with florescent lighting as well as post processing!

thanks again!

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16 Sheri Johnson August 3, 2010 at 5:41 pm

What I love about this is making me think about things, using different approaches and experimenting. I didn’t even read every single word here, but picked up my camera to just play around with HSS for a few minutes, knowing that without it I am pretty much limited to 1/250th and then the appropriate f stop. With HSS turned on I could shoot wide open at 1/1000th with flash at full power, which is actually quite fun especially with a bouncing 6 year old :)

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17 Maré August 3, 2010 at 6:42 pm

Thanks for taking the time to share this :) Now I have to go practice it :)

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18 Jason Malwitz August 3, 2010 at 7:00 pm

I think where HSS really excels is when using something like a 70-200 or even an 85mm. Its very easy to get the flash close by your subject and have more than enough power to even use a shoot through umbrella at 1/2000 or higher. I have been experimenting alot with this lately and have been pleasantly surprised with the results. I would definitely recommend using a supplemental battery pack attached to your flashgun of choice. It really speeds up the recycling time.

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19 Bryan August 4, 2010 at 11:34 am

Neil –

I have a canon T1i and a 580 ex ii that I use in ettl mode. The other day I was on a shaded L platform, and the day was very bright. I exposed properly for the sunlit background maybe around 1/200 for the max sync speed and f15. When I shot the picture, the background was exposed correctly, but even with direct flash (after bounce failed) my subject is severly underexposed. When I opened my aperature, my subject was properly exposed, but the background was obviously blown out. Can you take a moment to explain this phenomenon? Is this an application for a neutral density filter?

Regardless, thanks for taking the time to answer our questions. Everything on the site is great. Loved your book, can’t wait for the second.

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20 Neil vN August 4, 2010 at 12:49 pm

Bryan …

f16 is a pretty small aperture. (I think you meant f16 and not f15 ?)
So the chances are:
– you were too far away from your subject, or
– you had a diffuser cup on, or
– you had your flash in a bounce position, or
– you had your flash set to HSS mode.

Using a ND filter wouldn’t have helped you here, since it affects both the flash and the ambient exposure.

Neil vN

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21 plevyadophy August 4, 2010 at 2:36 pm

Flash Duration
==============

Hi Neil vN

Thanks yet again for a wonderful tutorial.

I have been meaning to raise this issue before, and the issue is one of flash duration. I have never seen you mention it in any of the articles of yours that I have read.

And I would be grateful for your view on the subject.

Based on my readings and the specific advise I have received, one ought not to set one’s shutter speed to a duration faster than the flash duration.

My Metz speelights have a flash duration of 1/200s at Full Power, so even if my camera can sync at 1/250, 1/320 or 1/500 I would never set the camera to a shutter speed faster than 1/200s for if I did I would in effect be cutting off some of the flash exposure as my shutter would close before the flash had time to discharge all of its light.

As far as flash duration goes, most companies, Nikon being a notable culprit, quotte flash duration figures according to the t5 standard. This is a very generous standard that gives figures for flash duation that are faster than a photographer would find applicable in real world use. The t1 standard preferred by Metz provides data that is more useful (realistic) to a photographer.

I had a Sony flashgun, for which there was no flash duration, and by doing a series of test shots at Full Power flash and a variety of shutter speeds I found that the flash duration was around 1/320s. I came to this conclusion by reference to the histogram for each shot; there was a clear difference at very fast shutter speeds (the test camera used can sync at any shutter speed up to one two-thousanth of a second).

Your views on this topic would interest me very much.

Warm regards,

plevyadophy

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22 William August 4, 2010 at 4:54 pm

Very helpful article as I experiment with HSS myself.
Thank you for putting the time into doing this for everyone.

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23 Scott Lightner August 4, 2010 at 10:09 pm

Hey Neil,

Long time! :)

“This idea that you go to a much higher shutter speed to control the available light when you use flash, is one of the biggest fallacies I’ve come across on the various photography forums. It simply does NOT work that way. The next section will show exactly why.”

Not a fallacy.
It works very well that way. You just need to use a lens with a leaf shutter and a pack (studio) strobe “;P

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24 Neil vN August 4, 2010 at 10:13 pm

Braggart! : )

Well, it works THIS way for us folks with puny D-SLRs

Neil vN

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25 Ifty August 9, 2010 at 10:19 am

Neil, I’ve heard that the old Nikons with hybrid shutters (the D70, D40, and I think the D100) can sync at any speed if the flash is non-TTL.

On these, would it be fair to treat flash exposure above sync speed (1/500 on those bodies) like a video light? As in, can you control flash exposure with shutter-speed, similar to HSS?

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26 Neil vN August 9, 2010 at 12:41 pm

Ifty .. there are several older D-SLRs with electronic shutters where you can go higher than the stated max flash sync speed. I tried to distinguish that here with this article by referring to cameras with a focal plane shutter.

The D70 has an electronic shutter, as well as the D2x (afaik), but not the D100. The original Canon 1D also had an electronic shutter, afaik.

As mentioned in this article, you do have to think of HSS flash as continuous light when you go over max sync speed.

Neil vN

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27 richp August 10, 2010 at 8:52 pm

Great article Neil. Question though. At the max sync speed, 1/200 for the D90 I use, if I close the aperture so I don’t blow out the background, will I need more power from my flash to make up for the smaller aperture? I’m trying to shoot indoors, with my subject against a wall of windows. I want what’s outside to be the background, without being blown out, and my flash to light the subject.

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28 Neil vN August 10, 2010 at 10:24 pm

Rich .. if you’re bouncing your flash for that scenario, you will most likely not have enough juice in your flashgun.

You will have to do something else to get an f11 range exposure for your indoors subject, to retain detail for the outside areas. For this, bounce flash wastes too much power to be a workable idea here.

Neil vN

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29 richp August 11, 2010 at 7:04 pm

Thanks for the reply Neil. The original battle plan from yesterday’s visit to the location went out the window, literally. The windows in the room face east over Boston Harbor. I also had a hazy sky and the sun coming up right at the wrong time. So I figured the sun that was coming in would bounce off the white wall behind me and light my subjects. That took care of the distance problem. For the fill flash I used your lesson on the ‘sunny 16th rule’, set my flash to TTL-BL and put my flash head forward. I also blocked as much as the reflection off the water as I could with the people I was taking pictures of. The exposure for the people came out great. Good skin tones. The hazy sky outside… Well, let’s just say we haven’t had many blue skies in Boston this summer. Thanks again, Rich

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30 Ramesh Meda August 30, 2010 at 7:06 am

Neil,

Cannot thank you enough. You helped me understand HSS, which for the longest time had confused me.

Your illustrations are (as usual) very informative and very usable. What I appreciate the most is your willingness to share and taking time off to pen your thoughts.

Much appreciated.

Regards,
Ramesh.

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31 sophie November 2, 2010 at 6:57 am

Dear Neil.
when saying
… I just shoot at maximum flash sync speed then to give me the most efficiency from my flash….
it could come across that the most efficient flash output you will get from your flash is at the max snyc speed. But if I am shooting slower than that my flash efficiency should be the same, it would only decrease it if going above into HSS, right?
Just want you to say yes, yes to that statement to reinforce what I am thinking.

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32 Neil vN November 2, 2010 at 7:04 am

If you don’t go over max sync speed, then your flash’s output is exactly the same for the same aperture .. regardless of your shutter speed.

However .. and this is a big however … when you are shooting in bright light, then you have to juggle your shutter speed / aperture / ISO settings. And then to help balance the flash against the available light, you’re usually better off shooting at max sync speed … since this will give you the widest possible aperture while remaining at max sync speed. That wider aperture will mean your flash has more reach. Or another way to view it, your flash will have more effect at the wider aperture.

Follow the tutorial again about max sync speed’s value. It all comes together between that article, and this article on high speed flash sync.

The key is that you need to consider these two broad scenarios …
1. using flash in low light / studio conditions,
2. using flash in bright ambient light.
… and then you’ll see the thought process makes sense.

Neil vN

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33 Andy November 14, 2010 at 2:52 am

Hi Neil, i need some input from you. I want buy some seamless paper (white, black, and gray) for portrait. What type of white and gray color (so many white and gray type) good for portrait from your experience?

Thanks Neil.

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34 Neil vN November 15, 2010 at 4:55 am

I use the Savage seamless paper backdrops, which come in a variety of colors. They do need some type of support system of stands and a cross bar.

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35 Irina November 19, 2010 at 3:07 pm

First, I absolutely adore your blog. Beeing new to flash photography I have learned a ton of info over 2 days of reading. Thank you SO MUCH for such clear explanation!!!

Now. I would like to try HSS in my little studio. My set-up 5D markII, 800 alien bees light with the soft box, reflector, sybersynk trigger and reciever. I would like to explore a possibility of shooting at the wide aperture with a studio lighting. Sorry for a stupid question (I am just learning studio set-up) how do I put my alien bees in a HSS mode? Is it something in a camera I have to set?

Thank you!

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36 Neil vN November 19, 2010 at 4:44 pm

Irina … afaik, you can’t take the Alien Bees into HSS mode. You need a dedicated speedlight for that. If you want a wide aperture in the studio, just dial down the power on your flash units, or use more diffusing. Or alternately, use a neutral density filter on your lens to get that wide aperture.

Neil vN

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37 Irina November 19, 2010 at 9:34 pm

Thank you a lot. I got your book and will read it front to back. Keep on doing such wonderful job for all of us!!!

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38 Hisham/Egypt March 27, 2011 at 2:38 pm

Thank you Neil for another great article, well clear comparison image between “Max Sync Speed & HSS”, the subject is high tech. indeed but you put it simple though, and I think the pretty models you hire makes the matter more optimistic. hehe c:/ thaaanks

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39 Vicco September 3, 2011 at 11:07 am

Hi Neil, great article!

My 2 cents: yes, this is a Catch 22 — if you use HSS mode, the flash power drops approx 2..3 EV, also if you use ND filters (there’s more flash power needed). The only way out seems to be to use those powerful portable flash units (>= 400 Ws). Or is there another way?

Yes, there is one, quite complicated at first sight, perhaps even you do not know this trick (do you?). I have only seen this trick used with portable flash units to make them capable of HSS, but it also works with speedlights :-))

*BUT* … the more powerful (=the slower), the better!!
This is how it works:
– but a TTL speedlight on the cam, set it to HSS and M (no preflash)
– fixate a combination of a photocell and a wireless transmitter in the near
– with this: trigger another speedlight, set on full power (long flash duration)

Trick is, that the main speelight is now burning throughout the exposure process, just like a constant light source. On full power these small flashguns should have flash durations of approx 1/1000 … 1/400 second.

More details and first results:
http://www.flickr.com/photos/galllo/5773362314/in/photostream

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40 Vicco September 9, 2011 at 9:17 am

Hi Neil,

thanks for this very interesting and eye-opening post!
Something I do not really get: You point out, HSS would be not a good idea when fighting direct sunlight, regarding the power-loss of approx 2..3 f-stops.

An example (please correct me):

(A)
Direct sunlight, camera settings: t=1/250 s, aperture = f/16, ISO 100
flash on non-HSS, full-power
(let’s define: this gives a good exposure)

(B)
Direct sunlight, …. camera settings: t = 1/1000, aperture = f/2.8, ISO 100
flash on HSS,

If my calculation is right, then this should give the same exposure, but with a really nice shallow depth-of-field.
In detail:

1/1000 s => -2 EV
f/2.8 => +4 EV
HSS => -2 EV

… sums up to 0 EV => same exposure as in (A), without the need for ND filters.
Does this make any sense?

Thanks and all the best
Vicco

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41 Neil vN September 10, 2011 at 3:37 am

Vicco .. check your math again.

Changing from 1/250 to 1/1000 is a 2-stop difference.
Changing from f16 to f2.8 gives you a 5 stop difference.

So those aren’t the same exposure settings.

Neil vN

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42 Vicco September 11, 2011 at 9:47 am

Hi there and thanks a lot!

Yes, sorry, 5 f-stops, sure. Now I checked my math again and did the corresponding tests. I think I got the rest of it right.

What was not that easy and clear for me was, that — when calculating with HSS — of course I have to deal with the exposure time. Like with ambient light.

Another aspect, that was not totally clear to me, is that HSS always means (approx) 1/4 flash power, on all settings. I struggled first thinking, that … with a manual setting of 1/8 in non-HSS, HSS could deliver also 1/8 (having still headroom left).
Anyway, here we go:

+++++++++++ An example (tested)

(1) Non-HSS setting
f/16, 1/200 s (irrelevant, just set on max on my Canon), ISO 100
Camera in M-mode, Flash in M-Mode, on 1/1 Power
Flash: 430 EX II, 24 mm Zoom
Camera: Canon 500D, M-Mode
This gives a perfect exposure now in my office room

=

(2) HSS setting
f/4, 1/1000 s, ISO 100
Camera in M-mode, Flash in M-Mode, on 1/1 Power

This gives *almost* the same exposure.
I got exactly the same with f/3.5 or with 1/800 (see below).

+++++++++++ Another one (tested)

(1) Non-HSS setting
f/11, 1/125 s (irrelevant, no ambient light visible down to 1/10 s, just set t >= 1/200 s), ISO 100
Camera and flash in M-Mode, flash on 1/2 power
… this gives for my scene a perfect exposure

(2) HSS-setting, giving the identical exposure (tested)
f/4.0, 1/800, ISO 200
all manual, hss, flash set on 1/2 power

Why?
The 1/125 s is irrelevant, we have to calculate with t_sync = 1/200 s (on Canon cams), because we compared the two flash modi on that max sync speed.
The comparison (tested) gave: Exposure (Non-HSS) = Exposure(HSS) – 2 EV

Furthermore: when dealing with HSS, now we have to include the exposure time in our calculation:

f/11 -> f/4: this means + 3 EV
ISO 100 -> ISO 200: this means +1 EV
Non-HSS -> HSS: this means -2 EV
1/200 -> 1/800: meaning -2 EV
——————————
sums up to 0 EV, same exposure … as measured…! :-)

All the best,
Vicco

// btw.: your two books are great!

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43 Ovidiu Suciu November 8, 2011 at 2:59 am

Thanks for this tutorials. They are the best I found.
My question is: Can I keep my camera in Aperture priority on lets say f5.6 and the flash on High speed sync and shoot my children in a park where the lightning differ without warring that when shutter speed goes below high speed sync the output of the flash is dimmed?

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44 Neil vN November 9, 2011 at 12:22 am

Ovidu … whether you’re out of range with your flash in high-speed sync, is something you’d have to check on the back of the flash’s display.

The way you describe could work … but you’d have to be aware of the distance limitation.

Neil vN

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45 B-Twien February 16, 2012 at 11:52 am

Hello Neil,

Thanks for your useful articles on High speed flash sync and Maximum flash sync speed…I tried copying your “exercise” under max flash sync speed, but could not get my shutter speed faster than the max sync of 1/250s on my Nikon D300s?

Putting it on Auto FP 250 did not do anything, since my camera keeps flipping back to the max sync speed of 1/250s? What am I doing wrong?

Does the flash needs to be handled manually instead of TTL?

Thanks for any input on this…

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46 JAMES April 4, 2012 at 6:37 pm

Hi,

Would I be able to use high speed sync using YN560 triggered by RF603 on a D70 body?

Thanks

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47 dennis May 20, 2012 at 8:14 pm

Hi Neil,

Very nice explanation, but you lost me at: “This is also obvious then why we need to be at maximum flash sync speed when working in bright light . . .”
I understand the “linearity” behavior of HSS, as you explain it, but I don’t see the connection to maximum sync speed. Why can’t I use 1/160 or 1/100 or 1/60 sync speed on a bright day, along with the small, appropriate F stop (like F/22)?
Also, I’m not understanding at: “For these examples, we had 1/250 @ f11 … which would, for ambient light only, translate to 1/2000 @ f4 . . . ” Actually, for the these examples, you’re showing various shutter and F stops. So, I’m confused as to why you’re referring only to 1/250. To me, ambient light is the amount of existing light. I’m not sure how you’re comparing it (“translate to”) to HSS. Not sure you feel like following-up on a 2 year old post. :) Thanks, Dennis

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48 Neil vN May 20, 2012 at 10:07 pm

Dennis … when I say 1/250th, it is meant to imply maximum flash sync speed, whatever it may be on another particular camera.

Now, about why maximum flash sync speed is important.

Let’s say you have a scenario where your subject is in shade, against a brighter background.
Let’s say it is 1/60th @ f/16 kind of bright.
f/16 is a small aperture. It limits what you can do with just one speedlight.
f/16 doesn’t allow the use of a softbox with a speedlight.

Now, bump your shutter speed to 1/250th, and then your aperture changes to f/8 …. and suddenly you’re more in the range of what a speedlight is capable of.

It’s as simple as that. The higher shutter speed gives you a wider aperture, which is more flash-friendly when shooting in bright light.

Neil vN

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49 Regina September 3, 2012 at 2:55 am

Hi Neil,

I’ve read some of the articles related to high speed speed and they don’t recommend using it as it will use more battery and thus, kill the flash faster. I’m going to take the photos of a wedding, there is a possibility that the day will be bright and sunny under midday sun. Most likely I have to use fill in flash with on camera flash for the portrait. I usually take photos indoors or under cloudy day. I’m just in a confused stage at the moment. As I don’t want to use up the battery or worse break the flash during that session. Is that true by using the flash on high speed sync that those will happen? I like to keep the ambient light there and try not to over power the sun either for this matter. It’s just to lift up the shadow. Can you please help me on this?

Thanks,
Regina

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50 Trev September 3, 2012 at 5:31 am

Regina,

No, you won’t kill your flash, it actually loses power as in the distance reachable is immediately almost halved the moment you go just 1/3rd of a stop over the sync speed, that’s all.

Keep your normal settings for full sunlight and depending on your camera, use the base ISO [100 Canon; normally 200 Nikon] and go to max shutter sync speed, usually 200th Canon, 250th Nikon and around the f11-f14 mark.

Now put your flash on, and dial the FEC on flash down to the -2 or -3 mark it will only lift the shadows. Obviously it’s shoot and see. Go get a white towel or somesuch, go outside in middle of day, and test your camera’s settings, with flash and see what you get.

Shoot RAW. :)

Links: http://neilvn.com/tangents/2008/06/13/photographing-in-hard-sunlight-with-and-without-flash/#comment-4176

http://neilvn.com/tangents/2008/05/11/direct-on-camera-fill-flash/

http://neilvn.com/tangents/2010/10/05/shooting-in-bright-sunlight-wedding/

I am in the tropics in Australia and 90% of my weddings are location, beach, park, generally under full sun, so I compensate various ways, sometimes I may go High Speed Sync, if I want a shallow depth field, but if you keep your eye on the back of the flash, it will actually tell you what distance/s are achievable with the camera settings anyway.

Oh, shoot camera in manual mode, perfect consistency. The only caveat would be the overcast or sun sifting in/out of clouds, that will play havoc with your metering.

Trev.

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51 Zach and Jody September 26, 2012 at 1:37 pm

Excellent article! There is so much miss-information on HSS and many people think you just speed up your shutter and overpower the sun! It is much more complex and you nailed it with this detailed info! Great work! -Zach

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52 Tanker10a November 20, 2012 at 1:00 pm

What blew me away about this article was that the material sounded sounded ever so familiar until it dawned on me that I have read a good part of them from Neil’s Book “On-Camera Flash” which I have been reading for the past few days…
Imagine that!

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53 Ben Mueller November 28, 2012 at 5:22 pm

Hi Neil, thanks so much for this article! Great work, and great enlightenment to find out the whole thing is merely a physical limitation of how the shutter works, and not something that can be engineered away. Also, I of course had fallen for the HSS-bright-sunlight thing as well! Thanks so much again!

Ben

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54 Bryan Striegler December 20, 2012 at 11:01 am

Hey Neil,

I’ve been struggling with trying to get dark, blue skies in my portraits, and I always thought that using a higher shutter speed would darken them and that I needed HSS. In the 4th point at the end of the article you said it isn’t true. What do you suggest then? What’s the best equipment/technique for the job? Do I need a neural density filter and a stronger flash?

Thanks

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55 Trev December 20, 2012 at 11:12 pm

Bryan,

Simply expose for your background, manual mode, then light them up with flash.

This is if of course there is something to work with in the first place regarding skies, and under normal sunny settings would be ISO 100, 250th or 200th depending on flash sync and f11-f13.

You should then retain whatever the light is in the skies, being from light to dark blue, depending on how much sky you include in the photo. Remember, under normal conditions it’s always much lighter at the horizon and gets darker as you look up.

Normally the darkest part of the sky is a fully 180 degrees from the side, in other words, the direct opposite side of the sky from the sun is the sky’s darkest part, but you then are looking at maybe trouble with direct sunlight in faces, eyes and squinting with harsh shadows under eyes, etc.

So, choose something slightly side-lit from sun and fill flash for normal sunny shooting, like this article.

http://neilvn.com/tangents/shooting-in-bright-sunlight-wedding/

Trev

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56 Neil vN December 21, 2012 at 4:59 am

Bryan .. you can change the shutter speed and go into HSS mode. However, it is a problem when you’re already at the outer limit of what the flash is capable of. If you now lose 1 – 2 stops of light because you’re in HSS mode, you took a step backwards in trying to over-power the bright daylight.

So what could you do? Change your aperture to get the available light to where you want.
If the DoF is too much, then a ND filter.

Or … go into HSS mode, but move your light closer, or add a second light.

As I said, these considerations really come into play if you’re pushing the limit on what your flash can deliver.

Try this article and see if it all makes sense:
controlling bright sunlight with direct off-camera flash

Also, check out this article: getting the most out of your speedlight and see if it all comes together for you.

Neil vN

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57 bharath March 22, 2014 at 9:41 am

Hi,
I have one major doubt in understanding high flash sync. I use fuji x100s . It has leaf shutter which help me go 1/1000th of sec at F/2 .

Can i use any old Nikon flash like SB28 ? to get this flash speed … ? ANYWAY I need to use flash in manual since Fuji don’t have any good flash.. And I love shooting manual …

I want to achieve this high flash sync..?? Does Flash also need to support this high sync speed ? or its just limiting in camera body ?

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58 Taro March 25, 2014 at 3:11 am

Bharath,
You can use SB-28.
According to: http://www.gock.net/2012/01/flash-durations-small-strobes/
The duration of SB-28 (I think it’s T.1 time, meaning the time it takes for the flash output to come down to 10% of peak) is 1/265 sec. at full (1/1) power, and 1/954 sec. at (1/2) power.
So you can set your SB-28 to 1/2 power manually, and count on using most of the output at 1/1000 sec. You may get a higher exposure with 1/1 power, but you cannot use all of it because the flash duration is longer than your shutter.

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59 Neil vN March 28, 2014 at 3:14 pm

The Fuji X100s syncs to around 1/500 without (much) loss in power. Higher than that, you can sync at the faster shutter speed, but there is around 1.5 to 2 stops of light loss from your flash for every stop you increase the shutter speed.

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60 Michele Stapleton June 2, 2014 at 10:11 pm

Neil, Thanks for this ever-so-helpful article, and thanks for being such a clear and concise writer. I confess, I started out by trying to read someone else’s article on HSS first, and after pulling my hair out, I stopped about midway through that article and switched to yours. Between the diagrams and the excellent writing, yours totally did the job. THANK YOU SO MUCH.

One question: Having started working with flash way back in the Sunpak Potato Masher Day, long before TTL, I’m very used to reading the distance scale when I want to use manual/power ratio for fill. Do you know if I’m going to be able to rely on the distance scale for HSS? (Or Auto FP as they apparently call it in Nikon?) Will the camera (D300/D800) and flash (SB900) be smart enough to see that I’m in HSS, with a shutter speed of 1/2000 for example, and calculate what distance my flash will be able to provide full power?

Thanks again!

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61 Michele Stapleton June 2, 2014 at 10:48 pm

Think I just answered my own question. The flash IS going to tell me the distance scale taking into account the power drop because the flash is constant and not just a single pop. How intelligent. (Might explain why Nikon wants $546 apiece for these suckers!)

Thanks again for all your articles!

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62 Neil vN June 4, 2014 at 11:40 am

Yes! The flash will tell you the distance on LCD display. If the distance doesn’t appear, it means your flash is in a bounce position. Just click it into the direct-forward position, and the distance scale will appear.

Unless of course, you cheaper out on the flash and have a flash without the distance scale. Then you’ll have to use the Guide Number of your flash.

And if course, the moment you add a modifier (like a softbox or umbrella), then the distance scale is meaningless.

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