The Phoblographer Answers: What is Flash Duration?

If you’re a wedding photographer, photojournalist, portrait photographer, food photographer, or you do any sort of work involving just the use strobism or flash then what you should also know about is one of the most awesome tricks of any strobist photographer: flash duration. A flash duration is crucially important to any photographer that wants to get serious about their lighting and can open up a whole world of creative possibilities to various creatives. It’s part of how Jaroslav created the Milky Pinups, and how many other photographers can stop high speed motion without the ability to crank up their shutter speeds.

In all honestly, I think it’s magic.

What is Flash Duration?

This is high speed sync: which cuts down on how much ambient light is in a scene

This is high speed sync: which cuts down on how much ambient light is in a scene

First off, flash duration is different from high speed sync and to recognize that, you should check this out.

The flash duration, in very layman’s terms, essentially takes over for the effects of shutter speed in an image to a point. They are measured in fractions of a second the same way a shutter speed is. On that train of thought, if you have a faster shutter speed, then you can stop faster moving motion in camera. Likewise, if you have a faster flash duration, you can stop faster moving motion in camera.

Fast Flash Duration, shot around the same time as the previous image in this post.

Fast Flash Duration, shot around the same time as the previous image in this post.

To recap when it comes to exposures with flashes/monolights:

  • Shutter speeds control the amount of ambient light in the scene
  • Aperture controls how much of the flash actually effects the scene when set to manual mode (changes in TTL)
  • ISO controls the overall sensitivity
  • Flash output is flash output

Flash Duration in Action

Chris Gampat The Phoblographer TriggerTrap Flash Adapter review images (3 of 12)ISO 2003.0 sec at f - 6.4

ISO 200 3.0 sec f6.4

See that image above? It stopped a very fast motion movement yet the shutter speed was very slow. Don’t believe me? Download the file. Do it!

At a 3 second shutter speed I was able to stop such fast moving motion. How? I was using the Einstein E640 monolight that has a very fast flash duration. The effects of the light going off made it able to stop the fast moving motion.

To a certain extent, a flash duration that is very fast can also give the same effects as less ambient light. This works best at the camera's max sync speed with your flash. Model: Asta Peredes.

To a certain extent, a flash duration that is very fast can also give the same effects as less ambient light. This works best at the camera’s max sync speed with your flash. Model: Asta Peredes.

So Why is This Important?

Model: Natalie Margiotta

Model: Natalie Margiotta

Fast flash durations can help you stop very fast moving moments, get sharper images (with its stopping power combined with specular highlights) and yield you more creative freedom with when you can shoot. Afraid of using a flash outside during the day? Go into the shadows and give it a shot.