Our customers at Pro Gear Orlando aren’t afraid to ask questions — which is great because we love answering them! 

One question we get asked a lot is about freezing motion, with customers often wondering:

Is it better to freeze motion with short flash duration or high-speed sync?

Our answer: Short flash duration.

Here’s why, but first let’s start with a short definition of flash duration.

Flash duration is the measurement of time for a flash tube to emit a single burst of light. The shorter this time is, the more effective the flash is at freezing motion.

In situations where the ambient light present is within your control, flash duration can act as your shutter speed, allowing you to decrease the time the flash is on and avoid exceeding your camera’s max sync speed. 

The benefit of this is seen when you compare your camera’s fastest shutter speed, usually 1/4000th to 1/8000th, to your specific light’s shortest flash duration, which can be as short as 1/12,000th to 1/80,000th.

Because the flash duration is simulating a much faster shutter speed, you’re able to freeze motion that would otherwise be blurry due to the high speed of the subject — and see your moving subject more clearly, sharply, and powerfully.

One thing to note: the shortest flash durations are always at or near minimum power output. So, as you increase your output power, the flash duration will get longer and you’ll see less effective freeze-motion shots.

So, why not High-Speed Sync or Hypersync?

Well, you can use high-speed sync or hypersync to freeze motion, but it’s not as effective. 

But first, let’s define high-speed sync and hypersync, just so they don’t feel left out.

High-speed sync creates a series of extremely quick pulses of light (instead of one solid flash) to ensure full coverage as the shutter travels across the plane of the sensor. 

Hypersync, on the other hand, triggers the flash just before the shutter opens and keeps it on until after the shutter closes.

High-speed sync and hypersync are best when you’re outside and the light is flat or overcast. They help you use your shutter speed to control ambient lighting so you’re not at the mercy of nature. 

Both high-speed sync and hypersync allow you to override the maximum sync speed of your camera, providing faster shutter speeds than standard flash syncs (usually 1/200 or 1/250). 

When using them, you’ll get a more even exposure across your subject, while also being able to balance with and incorporate the natural light around you.

One thing to note: the faster your shutter speed is, the less of the flash output is captured by the sensor.

The thing about high-speed sync and hypersync is that they’re only supported by some brands of strobes, and require a sync trigger dedicated to your specific camera brand (TTL dedicated). Flash duration, on the other hand, can be used with pretty much any flash unit and camera combination. So, if freezing motion is your goal and that effect can be achieved more powerfully with shorter flash duration, we say go that route and save some cash.

Verdict:

Short flash duration is the way to go to achieve your stop-action shots. It produces clear, sharp, and highly detailed images and can be achieved easily with whatever flash unit you’re using.

Flash Duration Times*

Profoto Pro 10: 1/80,000th (In Freeze Mode**)

Profoto D2 1000: 1/50,000th (In Freeze Mode**)

Profoto B10/B10+: 1/50,000th 500: 1/19,000th (In Freeze Mode**)

Profoto B4 Air 1000: 1/25,000th (In Freeze Mode**)

Profoto B1 Air 500: 1/19,000th (In Freeze Mode**)

Profoto Pro 8a: 1/12,000th

Broncolor Scoro: 1/14,000th

Broncolor Siros S: 1/8,000th

Broncolor Siros L: 1/7,400th

*Profoto uses the t 0.5 method to measure their flash duration while Broncolor uses t 0.1. Here’s an article from Sekonic explaining these different methods and a lot more: http://blog.sekonic.com/2017/05/11/demystifying-flash-duration/

** Profoto Freeze Mode, while shorter in duration, reduces color accuracy from frame to frame.

High-Speed Sync 

Air TTL Remote in combination with Profoto A1, B1, B10 and B10+, B2 250, D2, Pro 10 

— up to 1/8000th of a second with most camera systems

Hypersync

RFS 2.2 Remote in combination with Broncolor Siros S and Siros L

— up to 1/8000th of a second with most camera systems

To learn more about capturing movement, see this great article published by Broncolor:

https://www.broncolor.us/2016/02/rob-daly-capturing-movement-with-broncolor/

To learn more about the effects of high-speed sync, check out our post here:

https://boltproductions.com/lighting/profoto-high-speed-sync-test/