When a flash pops, it does so in a blink of an eye. Instinctively, photographers know that the pop of a flash can freeze the action in the scene so it must be fast, but because the light seems to linger in our eyes, it can seem somewhat longer. So the question I set to answer in this article is exactly how long a flash pop lasts.
In general, the flash duration on most speedlights is between 1/400 at full power, and 1/20,000 at low power. This trend is reversed on many studio strobes, which have a shorter flash duration at higher power than at partial power.
The real trouble with flash duration numbers is that they are easily manipulated. Unless you see the exact same setup test multiple flash units, it's difficult to compare the durations. There are many ways to measure flash duration, and each manufacturer uses their own numbers.
YN-560 Flash Duration
The following numbers are T1 numbers for the YN-560. This means 90% of the capacity of the flash output is measured. You'll see they are longer than the SB700 numbers below, but this is only because the measure is different. In reality, these flashes are very comparable in terms of flash duration.
By the way, if you'd like to learn how to use all the features on your YN-560 but you read the manual and were confused, check out the YN-560 manual that we re-wrote with lots of pictures. It's really handy and will surely teach you lots of new things about your flash.
| Flash Output Setting | Flash Duration |
|---|---|
| 1/1 | 1/313 of a second |
| 1/2 | 1/1359 of a second |
| 1/4 | 1/2,809 of a second |
| 1/8 | 1/4,950 of a second |
| 1/16 | 1/8,065 of a second |
| 1/32 | 1/12,626 of a second |
| 1/64 | 1/18,000 of a second |
| 1/128 | 1/23,000 of a second |
Source: Gock.net
Canon 580EX Flash Duration
The following are T1 measurements (similar to YN560 numbers above).
| Flash Output Setting | Flash Duration |
|---|---|
| 1/1 | 1/250 of a second |
| 1/2 | 1/919 of a second |
| 1/4 | 1/2,066 of a second |
| 1/8 | 1/3,759 of a second |
| 1/16 | 1/6,024 of a second |
| 1/32 | 1/9,470 of a second |
| 1/64 | 1/14,000 of a second |
| 1/128 | 1/20,000 of a second |
Source: Gock.net
Nikon SB-24 Flash Duration
| Flash Output Setting | Flash Duration |
|---|---|
| 1/1 | 1/231 |
| 1/2 | 1/794 |
| 1/4 | 1/1,366 |
| 1/8 | 1/3,425 |
| 1/16 | 1/5,208 |
Source: Gock.net
Nikon SB700 Flash Duration
Note: These numbers are only for the peak 50% capacity of the flash (T5). You'll see they are significantly faster than the YN-560, but it's not an apples-to-apples comparison.
| Flash Power Setting | Flash Duration at 50%(t5) | Flash Duration at 90% (t.1) |
|---|---|---|
| 1/1 | 1/1042 of a second | 1/305 of a second |
| 1/2 | 1/1136 of a second | 1/1,000 of a second |
| 1/4 | 1/2857 of a second | 1/2,300 of a second |
| 1/8 | 1/5,714 of a second | 1/4,000 of a second |
| 1/16 | 1/10,000 of a second | 1/5,250 of a second |
| 1/32 | 1/18,182 of a second | 1/8000 of a second |
| 1/64 | 1/25,000 of a second | <1/8000 of a second |
| 1/128 | 1/40,000 of a second | <1/8000 of a second |
Source: Canon USA and Nikon SB700 Manual
Compared to Studio Strobes
Studio strobes work differently than speedlights. Where speedlights almost always have faster flash durations at lower power, many studio strobes have faster flash durations at full power. This is because they use very different capacitor technology than a speedlight.
- The Profoto D2 claims to have the fastest flash duration of any speedlight at 1/63,000.
- The Paul C Buff Einstein e640 has a flash duration of 1/40,000 (T1) at 1/128 and 1/391 at 1/1.
Does Flash Duration Matter?
At 1/8 flash power and lower on most speedlights, flash duration really doesn't matter. It's already so fast that only in scientific shooting situations would any real-world difference be visible in photos.
However, at full flash power and 1/2 power, there would be many situations where some amount of blurring could be visible and not stopped by the flash pop. For example, if you were photographing someone riding a dirt bike like I did with Dave Black a few years ago, we saw significant blurring at 1/1 flash power.
However, there really is not a huge discrepancy between the flash durations of most popular speedlights. The inexpensive YN-560 which I recommend on the Recommended Flash Gear section of this site, is right on par with the Canon and Nikon flashes which cost 5x more money.
One major takeaway from this article is that if you're shooting something fast moving and you need to stop the motion, you'll be far better off using two flashes at 1/4 power than a single flash at 1/2 power.
Are Flash Duration Numbers Reliable? Manufacturers love to manipulate the numbers.
The numbers above are approximate and can easily be argued according to how they are measured and marketed by the flash makers.
Flash duration can be measured a few different common ways: (1) The duration for the peak pop of the flash to occur which releases about 50% of the light, (2) The time it takes to release 90% of the capacity, or (3) The time until the light is completely gone.
Generally, flash manufacturers advertise the first of these methods–the time it takes for the flash to release 50% of the flash power. Why? Because this number is shorter than the other numbers. Since the power does not all release at a continuous flow during the duration, there is value, however, in knowing when the peak capacity is released and how long that takes.
This is great if you’re really needing that duration to be as fast as possible and knowing that using several flashes can get you the power you need AND tha freezing characteristics you may be seeking. 🙂
Flash duration can be really more than a minor annoyance. In the early days, flash duration was so short, that it induced reciprocity failure, shifting the color response in the film emulsion Unfortunately, reciprocity failure is still alive and well, even in the world of electronic, digital imaging.
I’d love to see a comparison of using short flash durations vs shutter speed and high speed sync to stop motion. Which is better under which circumstance? Dave Black, for instance is a sports photographer that uses high shutter speed with a gang of speed lights like you’re showing here – I think he even uses ETTL settings on the flashes.
I made post here yesterday which seems to be gone now. It had a link to a photo showing how I’d used the technique described as well as another link to a blog post further describing the technique. Are links not allowed? I’m a newbie on the IP site and so I don’t know standard protocol here.
Comments made with the primary intent of linking people to their own site are usually not approved. We get too much spam on the site to allow it.
Thanks… That’s what I needed to know. 🙂
If one gangs 4 speedlights each at 1/8 power, will they trigger within several micro-seconds of each other to preserve a single 1/5000 sec light pulse at 1/2 power?
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