High-speed sync enables daylight flash at wide apertures by changing the way the flash fires.

According to the 1931 song, only “Mad dogs and Englishmen go out in the noon day sun.” Thanks to high-speed sync, flash photographers can now be added to the list. High-speed sync enables shutter speeds way beyond the norm for flash photography. It also opens up a new realm of creative opportunity.  Many shooters are intimidated by high-speed sync. In reality, it’s really easy to use if you have the right gear (say a Canon DSLR and a 580EX or a Nikon DLSR and an SB800).

Flash Photography Basics

I think of the amount of the flash as the duration of the flash. A speedlite [“speedlight” in Nikonese] firing at full power emits a longer burst of light than it does when firing at quarter power. When measured in a tiny slice of time, say a microsecond (one millionth of a second), the actual brightness coming out of the flash per microsecond is the same. At full power, the flash is just illuminating for more microseconds than it does at quarter power. [Note to uber-geeks: yes I know that it takes a few microseconds for the flash to reach full intensity and after peak intensity it falls off for a few microseconds, but let’s not be too uber.] Looking at this backwards, if you want to freeze motion with flash, then use a high-powered strobe set to a low power setting.

The amount of flash can be controlled by the photographer, by the flash or by the camera. In manual mode, the photographer dials the amount of the flash up and down. [I do this often. To find out when and why, you’ll have to wait for a future article. High-speed sync is way cooler than manual.] Some camera-mounted flash units have photo-sensors that will control the duration by measuring the amount of light coming back from the subject. [I think of this as “almost-matic” technology and never use it.] Today’s digital cameras have truly automatic technology in which the camera and the flash talk during the exposure. We refer to this as TTL – Through The Lens – flash. e-TTL in Canonese and i-TTL in Nikonese.

Sync speed is the fastest shutter speed that you can use during flash photography without “screwing up” the shot. If you use a faster shutter speed, a portion of your frame will not be illuminated by the flash. Ever have a flash photo with a dark band along one side? You shot faster than you sync speed. Of course, one shooter’s screw up is another shooter’s creative technique. Check out this video by David Ziser for an alternative look at purposefully  shooting faster than your sync speed.

The type of shutter in your camera (or lens) establishes the sync speed. View cameras (remember them?) and most medium-format cameras use lenses that have built-in leaf shutters with metal blades that open instantaneously from the center of the lens. Leaf shutters can synchronize with a flash at any shutter speed [technically, any shutter speed that is longer than the duration of the flash].

Single-Lens-Reflex cameras (film and digital) have shutters in which two curtains move across the focal plane. The interval between the curtains is the shutter speed. Essentially the exposure is a slit moving across the focal plane. For normal sync, SLRs must fire the flash after the first curtain is fully open and before the second curtain has started to close. Most DSLRs have sync speeds in the range of 1/125 to 1/250. At faster shutter speeds, there is no point when the entire sensor is exposed all at once – so normal sync is not possible.

Slow shutter speed = wide curtain gap, normal sync fine

Fast shutter speed = narrow curtain gap, must use high-speed sync

There are also cameras with electronic shutters that enable faster sync speeds (typically up to 1/500). Theoretically, electronic shutters can sync at any speed – but currently there are limitations caused by sensors over-heating… someday this will be really handy technology.

How High-Speed Sync Works

High-speed sync only works with dedicated TTL systems. The camera has to be able to talk to the flash. Further, you have to enable high-speed sync on the flash (Canon) or in the camera (Nikon).

With standard sync, the shutter has to be completely open when the flash fires. So, the camera fires the flash at the instant that the first curtain is fully open (“1st-curtain sync”) or at the instant just before the second curtain begins to close (2nd-curtain sync”). If you’ve ever seen a flash photograph taken at a really slow shutter speed where headlights of a car trail, that’s 2nd-curtain sync. [My cameras are always set to 2nd-curtain sync.]

With high-speed sync, the camera actually changes the way the flash fires. Rather than a single, strong burst, it tells the flash to send out an ultra-fast series of low-power, strobe pulses. Because the strobe pulses are so close together, the light appears to be continuous. So for the duration that the narrow curtain slit is traveling across the sensor, the flash is “always” on.

Canon’s Japan site has a useful diagram here. Fear not, it’s in English.

The upside of high-speed sync is that I can use virtually any shutter speed. The downside is that the output of the flash is greatly reduced. I often have to use several speedlites to get enough light when shooting at high-speed.

Freedom of Aperture With High-Speed Sync

High-speed sync gives me more creative freedom (aka: wider apertures). This is the main reason that I use it. Let’s say that I’ve been commissioned to shoot a portrait of a rising music star and that the only time she’s available is for 20 minutes at noon. Given that the sun is straight overhead, I’ll have to fill her face somehow. If I use a shiny reflector, she’ll squint and probably complain. So, I want to use a fill flash (or two) pushed through a white umbrella to soften the shadows.

With regular sync, the fastest I can shoot on my Canon 5D is 1/160. [Yes, I know the Canon specs say 1/200. But, in my part of the universe, it’s really 1/160.] So, under the blazing sun, at 1/160, my widest aperture for a good exposure is f/13. That’s way too much depth-of-field for my portrait style. One option, would be to slap on my Singh-Ray Vari-ND filter and dial in several stops of neutral density. But, then I can’t see the magical expressions on my subject. The better choice is to turn on the high-speed sync on my 580EX (literally a quick button push). Now I can (almost) pick the aperture that I want to use. The reality was that there was too much sun. At 1/8000, the widest aperture I could get was f/5.6 – still, much better than f/13.

Taming The Sun With High-Speed Sync

Another benefit of high-speed sync is that you can overpower the sun with a small speedlite or two. In the photo above, you’ll note that the sky and background (basically, everything lit by the sun) is underexposed. Why? Two reasons. I wanted to make my subject the dominant element (aka: the brightest part of the picture). I also wanted to reduce the competition between the geometry of her arms and the geometry of the lattice. How? I set my overall exposure at -2 EV and my flash exposure at +2 EV. That’s about all the thought I put into it. I let the digital gnomes in my camera do the calculations.

In the following shot, you’ll see the underexposed daylight at left and the effect of the high-speed sync at right.

At left: Daylight only. At right: Canon flash at high-speed sync.

At left: Daylight only. At right: Canon flash at high-speed sync.

Setting Up High-Speed Sync

On Canon 580-series or 430-series speedlites, your flash must be set to ETTL mode. Then push the H-button until you see the H-icon on the screen. You are now in high-speed sync mode. Frankly, I keep high-speed sync on all the time. I shoot in aperture-priority (AV) mode 99% of the time – meaning that I’m almost always more concerned about controlling depth-of-field than I am about stopping motion. There’s no harm in leaving high-speed sync on. When I dial to an aperture that enables a shutter speed of 1/200 or slower, the camera automatically operates the flash at normal-sync mode – meaning that the full power of my speedlite is available.

On Canon Speedlites: Mode must be ETTL, then push the H-button

On Canon Speedlites: Mode must be ETTL, then push the H-button. That's it. High-speed sync is activated.

On Nikon systems, it’s called Auto FP High-Speed Sync. As I understand it, you activate it in your camera rather than on the flash. Nikon shooters are encouraged to add comments relating to the specifics for their cameras.

Watch High-Speed Sync In Action

Watch this video of Joe McNally shooting high-speed sync in the sand dunes of Dubai. Thanks to the Strobist, David Hobby, for putting it together and launching it on the web.

Why did Joe use so many speedlights? You’ve already learned that high-speed sync greatly reduces the output. So if you have one speedlite and want to double the output (get another stop of light) you have to add a second speedlite. Then if you want another stop of light beyond that produced by two speedlites, you have to add two more speedlites. If you want third stop of additional light, you have to add four to the (one plus one plus two). So for three stops, you went from one light to eight. [Stay tuned… I’ve decided to round up as many 580EXs as I can and start firing them off en masse for a future article on this most-confusing concept.]

Wireless, High-Speed Sync with RadioPoppers

The opening image was shot using three 580EXs, a 430EX and a mess of RadioPoppers. One 580 was camera mounted with the Popper transmitter. It acted as the Master, but did not fire during the shot. The other three speedlites were mounted ala McNally on a C-stand at camera right and zoomed out to 105mm so that the light was concentrated along the length of the subject.

The Poppers provided eTTL control without too many hiccups.  The biggest issue was making sure that the fiber optic was placed exactly over the sensor. Not a biggie after we figured it out. Using the Poppers enabled me to forget about maintaining a line-of-sight between my Master and Slave units. I could work with my subject without concern for where the rack of speedlites stood. In short, I think RadioPoppers are great. New technology, yes. Rather expensive, yes. A bit buggie, yes. Able to do something that no other gadget can, YES. More on the Poppers to come soon.

RadioPoppers + Canon 580EXs = Wireless, High-Speed Sync

RadioPoppers + Canon 580EXs = Wireless, High-Speed Sync

104 Responses to Flashing At High Noon… or Simple Truths About High-Speed Sync

  1. Ewen says:

    Nice article, very informative. However would like to point out one little thing.. that is that the whole off camera HSS thing was first developed by Minolta in the mid-late 90’s and was a feature in their last film bodies (Dynax 7 & 9) and then followed into the digital SLRs (Dynax 5D & 7D) and lives on today in the Sony Alpha system where it’s available on the entire range.

    Much like the Canon/Nikon versions, it’s line of sight except on darker situations and uses the pop-up flash as the master. The new A900 however, does not have a pop-up flash and requires the new HVL-F58AM dedictated strobe as the master. The good thing with the new units is that the power/output of the slaves can be controlled directly from the Master flash, similar (I think) to the Nikon CLS system.

    • Syl Arena says:

      Ewen – Great info. Many thanks. I have a hard enough time staying up with Nikon (having spent the past 25 years as a Canon shooter). Nice to see that Sony is nipping at the heals of the other guys. It’s all good for us.

  2. Thanks for the article. It's good to hear some in depth info about the RPs… been considering them, not sold yet.

  3. Thanks for the article. It’s good to hear some in depth info about the RPs… been considering them, not sold yet.

  4. […] learning links for December – Syl Arena has an article about using high speed sync with your small strobes like the Canon 580EX or the Nikon SB-900. You can sync them up to 1/8000 sec! – On the same theme, […]

  5. […] Simple Truths About High-Speed Sync | PixSylated […]

  6. […] Arena is a California-based shooter who also loves to play with lights. His post on high-speed sync explains it about as well as it can be explained. Overall good photography blog too. He also loves […]

  7. Robin says:

    A great subject, I have just got the Nikon D90 and can fire the SB-600 using CLS @ 1/500 as long as the on camera flash is set to — so that it does not fire but emmits the signsl.

  8. Robin says:

    A great subject, I have just got the Nikon D90 and can fire the SB-600 using CLS @ 1/500 as long as the on camera flash is set to — so that it does not fire but emmits the signsl.

  9. Albin says:

    You mention 2nd curtain sync and it being necessary to mix flash and motion, to my understanding that is incorrect. The only difference is that you “freeze” the motion at the end instead of at beginning of the exposure.

    • Syl Arena says:

      Albin – You're right, in one of the comments, I said "if I wanted to convey a sense of motion (in which case I need a slow shutter speed and 2nd-curtain sync).]" I'm referring to a matter of personal vision, not technique. My vision of conveying motion with speedlights is that the subject is frozen at the end of the movement. Hence, my use of 2nd-curtain. If I wanted to convey a spirit departing from a body, the I would use 1st-curtain.

  10. Albin says:

    You mention 2nd curtain sync and it being necessary to mix flash and motion, to my understanding that is incorrect. The only difference is that you “freeze” the motion at the end instead of at beginning of the exposure.

    • Syl Arena says:

      Albin – You’re right, in one of the comments, I said “if I wanted to convey a sense of motion (in which case I need a slow shutter speed and 2nd-curtain sync).]” I’m referring to a matter of personal vision, not technique. My vision of conveying motion with speedlights is that the subject is frozen at the end of the movement. Hence, my use of 2nd-curtain. If I wanted to convey a spirit departing from a body, the I would use 1st-curtain.

  11. Dan Watson says:

    I see from the photo here that you used 3 Speedlights and I assume (1 to control it). 4 Speedlights and 4 Radio Poppers is not an inconsiderable investment. So, firstly, I'd like to know shooting thru an umbrella for soft light, at close range, would 1 or 2 Speedlights be enough to light a bride, say in afternoon sunlight, while underexposing the sky 2 stops? (sorry, I know that's similar to another question I asked in another post).

    Secondly, I understand the need for a system like a Radio Popper because in order to use high speed sync you need the encoded cross-talk between the flash and camera to sync the flash. I also understand that the only other system allowing Hi speed sync is the new Pocket Wiz but with w/ that system you don't need the on-camera Speedlight. So, what's your opinion on the Pocket Wizard ETTL system vs. Radio Poppers? I hear the PW also allows a "normal" sync speed increase of up to an additional stop because of the commo protocol that they use. (and No, I am in no way associated with Pocket Wiz; just have done & am doing a little due diligence & want to know which to buy).

    Thanks in advance,

    Zpowderhound

  12. Dan Watson says:

    I see from the photo here that you used 3 Speedlights and I assume (1 to control it). 4 Speedlights and 4 Radio Poppers is not an inconsiderable investment. So, firstly, I’d like to know shooting thru an umbrella for soft light, at close range, would 1 or 2 Speedlights be enough to light a bride, say in afternoon sunlight, while underexposing the sky 2 stops? (sorry, I know that’s similar to another question I asked in another post).

    Secondly, I understand the need for a system like a Radio Popper because in order to use high speed sync you need the encoded cross-talk between the flash and camera to sync the flash. I also understand that the only other system allowing Hi speed sync is the new Pocket Wiz but with w/ that system you don’t need the on-camera Speedlight. So, what’s your opinion on the Pocket Wizard ETTL system vs. Radio Poppers? I hear the PW also allows a “normal” sync speed increase of up to an additional stop because of the commo protocol that they use. (and No, I am in no way associated with Pocket Wiz; just have done & am doing a little due diligence & want to know which to buy).

    Thanks in advance,
    Zpowderhound

  13. […] wordt de kracht van je flits verminderd. Meerdere speedlites gebruiken is hierbij de oplossing. http://pixsylated.com/2008/11/simple…gh-speed-sync/ __________________ Website http://homepage.mac.com/kristofpattyn/site/ Canon 5 D – 30D, glas van […]

  14. @ dan — you could avoid the RP and PW stuff and just use the built-in wireless capabilities. (though then you introduce line-of-site issues, of course)

  15. @ dan — you could avoid the RP and PW stuff and just use the built-in wireless capabilities. (though then you introduce line-of-site issues, of course)

  16. […] sync, as I’ve explained elsewhere, changes the way that a Speedlite fires. Rather than one big burst, the camera tells the strobe(s) […]

  17. Will King says:

    Syl,

    I'm getting to the party late but I rediscovered your blog after meeting you last week at Joe's One Day Lighting Seminar. Sorry for almost blinding you with the 3 580EX IIs. ;)

    My question is regarding your statement about HSS. "On Canon 580-series or 430-series speedlites, your flash must be set to ETTL mode."

    I could be mistaken but I'm pretty sure that I was able to set off 3 580EX IIs as slaves in HSS with another 580EX as the master in manual mode. I'll test it again this week just to make sure.

    Will

  18. Will King says:

    Syl,

    I’m getting to the party late but I rediscovered your blog after meeting you last week at Joe’s One Day Lighting Seminar. Sorry for almost blinding you with the 3 580EX IIs. ;)

    My question is regarding your statement about HSS. “On Canon 580-series or 430-series speedlites, your flash must be set to ETTL mode.”

    I could be mistaken but I’m pretty sure that I was able to set off 3 580EX IIs as slaves in HSS with another 580EX as the master in manual mode. I’ll test it again this week just to make sure.

    Will

  19. Praveen says:

    Hello Syl,

    I am just learning about high sync flash. One thing that I didn't understand from your article: During high sync, if the flash is "constantly" on during the the time the curtain slit travels across the sensor, and if the light level produced by the flash is constant during this period, then how does the FEC work? Presumably, during normal (non-FP) flash, -FEC would reduce the duration of the flash and +FEC would increase the duration of the flash. However, during FP flash, the duration would be fixed by the shutter speed…..what am I missing?

    Praveen.

  20. Praveen says:

    Hello Syl,

    I am just learning about high sync flash. One thing that I didn’t understand from your article: During high sync, if the flash is “constantly” on during the the time the curtain slit travels across the sensor, and if the light level produced by the flash is constant during this period, then how does the FEC work? Presumably, during normal (non-FP) flash, -FEC would reduce the duration of the flash and +FEC would increase the duration of the flash. However, during FP flash, the duration would be fixed by the shutter speed…..what am I missing?

    Praveen.

    • Syl Arena says:

      Praveen –

      Great question! You’re missing the fact that the flash power can be dialed up or down by camera through FEC. The speedlite can fire in High-Speed Sync at full-power. It can also fire in HSS at 1/2, 1/4, 1/8, 1/16, 1/32… Keep in mind that the effective range of a speedlite at any power level in HSS is substantially shorter than it is in standard mode.

  21. Praveen says:

    Syl,

    Thanks for the quick response. But what you are saying here seems to be contrary to what you said above in the article:

    "I think of the amount of the flash as the duration of the flash. A speedlite ["speedlight" in Nikonese] firing at full power emits a longer burst of light than it does when firing at quarter power."

    This seems to imply that flash will always light with the same "brightness"…only the time duration changes when you adjust the power level.

    Praveen.

  22. Praveen says:

    Syl,

    Thanks for the quick response. But what you are saying here seems to be contrary to what you said above in the article:

    “I think of the amount of the flash as the duration of the flash. A speedlite [“speedlight” in Nikonese] firing at full power emits a longer burst of light than it does when firing at quarter power.”

    This seems to imply that flash will always light with the same “brightness”…only the time duration changes when you adjust the power level.

    Praveen.

  23. Philip Evans says:

    Dear Syl

    Love your insights – does the high speed sync work as well with my older 20d – 550ex combo. High speed sync is a two button push on the 550ex but does it do the same as you describe

    I have found your website great for my being a Canon baby from the days of the ae1-P (in black of course)

  24. vivian says:

    Hi Syl,

    I am often hired to shoot at the finish line at running events like marathons and triathlons. It's not unusual for me to shoot 5,000 to 7,000 images, rapid-fire style, in the span of 4 to 6 hours

    The runners often wear hats which cast a shadow under their eyes so I would like to use my 580EXII as fill.

    Would it fry my 580EXII over the course of 4 to 6 hours? (I have fired 3 shutters in 2 years as a sports shooter, so I am weary of frying more gear).

    I was thinking of using it in manual mode, using high-speed synch, but powering down the flash to 1/8th or 1/16th power to save on both battery life, recycle time and to not fry the flash unit.

    The runners are typically about 10-15 away from me and I need to use a shutter speed no slower than 1/500th to stop motion.

    Daylight conditions will change through out the shoot. From cloudy and sometimes rain in the morning, to blazing sun in the afternoon.

    Please let me know how you would approach this.

    Thanks for any help. It is much appreciated.

    Vivian

  25. Brian Carey says:

    This is fabulous! This is my first attempt at high speed sync flash, @ 1/6000 sec http://www.briancareyphotography.com/People/Portr

  26. Robert Orsa says:

    I like to shoot with my flash off camera. I am currently using Cyber Sync’s by Paul C Buff which I love but they are manual, not TTL. I’m not about to invest in Radio Poppers also. I have an off camera cord for my Canon 580 EXII but it’s only a couple of feet and coiled. I’ve been researching adding an extension to the off camera cord but it’s quite complex to create. Does anyone make an off camera cord that is around 15 feet (or more) that does not cost an arm and a leg?

  27. […] shooting at a -1 or -2 stop flash exposure compensation. Here is another explanation of HSS use. Simple Truths About High-Speed Sync | PixSylated by Syl Arena ? Honestly-Biased Insights on Photogra… __________________ Members don't see ads in threads. Register your free account today […]

  28. […] is a neutral density filter a good substitute. For more details on HSS, check out these articles: Simple Truths About HSS, Dimming The Sun – Part 1, and Part […]

  29. jlorenzo says:

    Interesting article, however I used a Canon 5D MK II, 1x Quantum T5d-R flash mounted on boom and Pocket Wizards to accomplish the same effect here at the beach in Perth, Western Australia which is quite bright.

  30. Not 100% in line with what Rex says about the use of many strobes.
    "The only reason to use many strobes is when you must place your lights far from the subject or you're using an umbrella or soft box." It is not just a matter of power but also of shape of the shadows. Portrait Photographer

  31. Chris says:

    Anyone have any experience with the Cheetah 360? It is supposed to pack the wallop of 6 x Canon 600ex rt.

  32. […] high-speed sync (HSS) many times on PixSylated. [For an introduction to HSS, check out this Simple Truths article.] The short version is that HSS changes the way the Speedlite fires. HSS enables the use of […]

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