High Speed Sync Versus a Neutral Density Filter to Overcome Bright Sunlight in Portraits



For several years now I have used high speed sync (HSS) in order to light portraits in full sunlight at a wide aperture. If you’re unfamiliar with HSS, it allows you to shoot at shutter speeds that are higher than the native sync speed of your camera (usually 1/200 or 1/250 of a second, read your camera and flash manual to find yours) while still using speedlights. The reason this ability is so enticing is that you can shoot flash-lit images at wide open apertures in full sunlight, allowing for a shallow depth of field. Normally if you were using a flash, your maximum shutter speed would be at 1/200 or slower, meaning that you would need to close your aperture down in order to get a proper exposure in the sun.


Raw image shot at f/29

How HSS works is that the flash will begin pulsing light, just before the shutter opens, since the exposure is so short. The problem with this is that much of the output of the light is lost in the pulsing process, meaning that you need more flash units to achieve a decent output. For example, when I am shooting at 1/8000th of a second, I need to combine four flashes, on one stand, in order to light a subject that is about five feet away. And that is without any modifiers, like an umbrella or soft box. The other issue with HSS is that not just any flash and trigger system will do the trick. You need to have gear that will communicate information from the camera to the flash.

A couple systems that can do that are the PocketWizard Flex TT5 and Mini TT1, or the RadioPopper PX system. Since most photographers don’t already own one of these triggers systems, this means starting from scratch, which isn’t cheap. I personally opted for the RadioPopper system, since the PocketWizard Flex system for Canon was super glitchy. The RadioPopper system wasn’t perfect either. Just the amount of batteries alone, for four Canon Speedlites with triggers, including a ST-E2 transmitter for the camera, required 27 batteries. Even though they were mostly all rechargeable (the ST-E2 required the hard to find 2CR5 battery), imagine trying to troubleshoot a misfire. Did the batteries need changed in one of the transceivers or was the speedlite misaligned, obscuring the sensor? Or imagine that one of the speedlites’ batteries may be slightly more drained than another, causing only three of four lights to fire. This made the overall exposure fluctuate with every frame.


Raw image unlit


Raw image, 1/8000 @ f/2.8

I recently decided to compare HSS against using a variable neutral density (ND) filter. ND filters screw on to your lens and cut down the light that hits the sensor, thus allowing for a wider aperture in bright light. This allowed my shutter speed to stay at or below the sync speed cutoff, allowing the full strength of the Speedlite to light my subject. This meant that I wouldn’t need to transmit ETTL information (sell the RadioPoppers) and it meant that I would need fewer Speedlites (less batteries).

After setting my ISO as low as it would go (50), my shutter speed as high as was allowed (1/200th on the Canon 5D MarkII), and my Speedlites at their full output, I dialled down the variable ND until the ambient light perfectly balanced with the light from the flash.


Raw image unlit


Raw image, 1/200 @ f/4

Some people have pointed out that there could be the issue of a color cast with certain brands of ND filters. I have not experienced any issues with the ProMaster brand. However, it’s important to keep in mind that if you are shooting directly in to the sun, there will likely be glare in your image, causing a possible color cast or the image to appear washed out.

Note that this experiment was done using Canon 430EX Speedlites with RadioPopper PX triggers. I’ve since sold them all, opting for the cheaper, sturdier and more powerful LumoPro LP180 with PocketWizard PlusX triggers. Now with one bare bulb flash, and a variable ND filter, I can effectively cut the ambient light while fully lighting a subject at f/1.4 in full sunlight.

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Nick Fancher is a portrait and commercial photographer based out of Columbus, Ohio. His clients include The New York Times, ESPN Magazine and Forbes Japan. He specializes in a no-frills, run and gun approach to lighting. His two ebooks are available here. You can connect with him on Instagram.

  • Thanks for your answer, I will keep it in mind. Also I was thinking later that the sun´s reflection in the model´s face could a little annoying.

  • dargahi

    i should buy a good camera , I don’t think my camera supports High speed sync anyway .Otomatik kap?otomatik kepenk

  • SandmanUSD

    So I notice you used two COMPLETELY different shots to “prove” that the HSS wasn’t as effective… yet in the HSS shot, you shoot wide, with the flash obviously further away from the subject, you shoot at 2.8 and have the sun directly in the shot… which was obviously a way to make it so you NEEDED 1/8000 to get a correct exposure on the background… which of course then cuts the power down tremendously on the flashes… coupled with how far they were away…

    Yet, on the ND shot, you are much closer to the subject and don’t have the sun in the shot at all, and are shooting at f/4, 1 stop narrower… so you are using aperture to help control the background by 1 stop, then not having the sun in the shot at all, requiring obviously a lower shutter speed (without ND) to get the correct exposure… and of course, your closer to your subject so you can get your flash closer, since what you don’t mention AT ALL in this article is the fact that ND filters cut down on ALL light, including those from the flash by whatever power your ND filter is… in fact you sort of made it sound the opposite:

    “allowing the full strength of the Speedlite to light my subject.”

    The full strength of the speedlight, minus whatever the ND filter power is…

    And since the shots were obviously VERY different… what this really proves to me is that you tried to get the same shot with the sun in the image at 2.8 with the flash further away from the subject with the ND filter, but it was COMPLETELY blown out, because 1/8000 to 1/200 is 5-1/3 stops… which means your ND filter would have to have been at least that just to get the background under control… (which I notice you never mention the ND filter strength in there…) which means your single flash would have to have been 5-1/3 stops stronger just to overcome the ND filter… Which means you would have been shooting at the equivalent of 1/64 +.7 give or take flash power…. no way on earth you would have been able to properly expose that subject from that distance with that flash power any more than you could with the 1/8000 HSS shot…

    So you did what any article writer does to “prove” their point… you fudged the numbers to make it the outcome you wanted to make it… and wanted everyone to believe… that the ND filter somehow was magically better at this than HSS…

    PS: Another thing, you eluded to the fact you used 4 flashes in the HSS test shot of the subject, by the fact you said right after the shot:

    “and it meant that I would need fewer Speedlites”… when you actually said above the test shot that you needed that many to properly expose the shot….. which the HSS test shot is in no way or form “properly exposed”…

    Which you then say: ” my Speedlites at their full output” … indicating you had multiple speedlights for the ND test shot…

    TOO MANY HOLES in this article… I’m sorry… I don’t buy it… you are pushing your agenda and skewing the facts to suit your desired outcome…

    Put up an EXACT shot where you NEED a 1/8000 shutter speed to control the ambient, and then use the EXACT same composition on the ND shot with the same number of lights… I think we all know what that outcome would be, and it wouldn’t look in favor of the ND filter any more than for the HSS…

  • You figured me out. Big Filter has me in their deep pockets. In case you actually want to know, here are the facts. I have a 70-200 f/4L IS lens, not a 2.8, so no I did not close down the aperture on the ND shot. If anything, that shows just how much more effective the filters are, since I lost a stop and a half and still had enough light. Second, I wasn’t manipulating my angles to prove a point. These shots were taken within 15 minutes of each other, and no, I didn’t change the distance from the light stand to the subject. Third, when I said ND filters allow me to use “the full strength of the Speedlite to light my subject” I meant that I was getting the full length of the flash burst and not just a fraction of it, as is the case in HSS mode.

    The only agenda I am pushing here is that you one can save a lot of money, time, frustration and batteries by using ND filters instead of HSS. Disagree with me? Fine. I’ll stick to my filters.

  • SandmanUSD

    So the 1/8000 2.8 shot showing how “bad” HSS was, was just fabricated? Since you don’t have a 2.8 lens but it says it was taken at 2.8?

    You did in fact completely change the shot… there is no sun in the second shot, which means you didn’t have to overcome the sun with your ND filter, so that gave you much more wiggle room in your flash power to then stop down to f/4 to keep the background even more in control… all of which didn’t show how much better an ND filter was over HSS, since you are comparing apples and oranges…

    You are saying HSS required to hit 1/8000 to get the background with a sun under control is somehow worse than a ND filter with no sun, which obviously required far slower shutter to keep that under control…

    At very least the test is very poorly done and shows nothing… at worst you are trying to push misinformation on people on purpose… Either way… information is just inaccurate here.

  • First of all, I hope you’re not anyone’s parent or spouse. Second of all, the 2.8 lens was a different lens. It was a 24-70 f/2.8. Third and finally, the conditions were the same in both shots- a cloudless, midday sky.

  • Gabriel

    Thank you for the test and ignore the usual trolls man.
    I have been pondering about the two and was thinking that for the money, just getting a good quality (not a piece of junk) ND filter makes more sense for me at least.
    This just proves it.

  • Johan Bauwens

    When using a ND filter, you lose autofocus, so how can you focus on the model ? Its should stand still !

  • Johan Bauwens

    What kind of comment is that ? Stick to the topic and don’t get personal !

  • Val

    Thanks for the great article. But I’m confused. You tell you use LumoPro LP180 with PocketWizard PlusX triggers. But what is the receiver?

  • AskFelix

    For simplicity, assuming the ND shot is taken under the same harsh ambient lighting as the HSS shot under ISO 100, the equivalent ambient exposure for 1/8000 @ f/2.8 is 1/200 @ f/18 or 1/200 @ f/4 with a variable 4+1/3 stops ND filter. For the ND shot, if the ISO is reduced to 50 (from 100), a variable 3+1/3 stops ND filter is used instead. Regardless, the ND shot has the same equivalent ambient exposure as 1/200 @ f/18 @ ISO 100. This is the number we will work with going forward since it also has the same effect as the ND filter in a flash exposure (i.e. 1/200 @ f/4 @ ISO 50 with 3+1/3 stops ND filter).

    Following the sunny 16 rule, 1/200 @ f/18 @ ISO 100 will mean that the ambient light is 1+1/3 stop underexpose. That is why the background is darker and gloomy under bright sunlight.

    For most speedlites at full power, they can expose properly to at least 6 feet @ f/16 @ ISO 100. So for f/18 @ ISO 100, one single speedlite can expose properly to at least 5 feet. If two speedlites are used, then at least 7 feet. If 4 speedlites, then at least 10 feet.

    As such, Mr. Fancher has no problem using flash with ND filter and can even expose properly with a single speedlite placed at 5 feet from the subject. Using ND filter is always more flash efficient compare to HSS.

  • AskFelix

    I am pro ND filter, but there are circumstances that HSS rules when higher shutter speed (above flash sync speed) is required to freeze certain action shots and when quick Auto Focus is needed.

  • AliNoorani

    I didn’t know that you lose AF with ND filters. seems logical now that I think about it

  • AliNoorani

    I ended up here again only to find my comments here from a year ago! 🙂
    this time around, I just felt why should one use 5 speedlites and 30 batteries in HSS to shoot a portrait in the sun, while you can do it with a strong strobe and a battery pack?
    See you next year LOL

  • Brooklyn Born

    The lower end Nikon cameras (3000 series, 5000 series) are High Speed Sync compatible. Nikon is very different from Canon. With Nikon, both the camera and speedlight have to support HSS. With Canon, I believe only the flash does.

  • Roli TheOne

    That is the case depending on how dark your ND and the ambience is. A 1000x ND will most likely be too dark for AF to work. A subtler ND, as you would need for this kind of stuff should work.

  • ninpou_kobanashi

    1000xND = Lens Cap?

  • Caravan Film Crews

    HSS almost always becomes your key light. The only reason why you need hss is because the background is overpowering the foreground. The only way hss becomes fill is if there are 2 off camera flashes, or if there is already a very bright source, close to the subject, that allows you to expose for sky while also exposing for subject, and you added HSS flash to fill shadows (like under chin, or bridge of nose). It is not fill. ALSO if you’re using a high shutter, you’re cutting out light from the whole image. You’re letting in the same amount of light, but for WAY LESS time. ND filters will stop light from entering (in a different way, albeit), but accomplishing roughly the same feat, the ONLY exception is motion blur.

  • Caravan Film Crews

    Dude, he’s not saying HSS is bad. HSS is totally awesome. But if you’re having trouble with batteries, and expensive strobes and all that jazz, throw an ND filter on it. You can get roughly the same effect, minus affecting the motion blur. That’s all, dude. You’re taking this way too personal. I really don’t think this article was written about you.

  • Caravan Film Crews

    This comments section has become an opinion box for lots of people who are unfamiliar with hss and nd filters. Yeah, you may have used them. And that’s cool, but that doesn’t mean you can refute what is in the article.


    I’m in the same boat, and indeed thanks Nick !

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