Flash duration is one of those terms you hear in the world of flash photography but may not know exactly what it is, or why it matters. It’s really quite simple, and pretty much exactly what it sounds like. The measurement of time from when the flash begins to fire until it’s completely off is what’s known as flash duration. Like a light bulb filament slowly burning off when it’s turned off, a flash tube does the same thing, but much quicker.
The reason flash duration is important is because in certain situations where you can control the ambient light, it can act as your shutter speed. This allows you to freeze motion without exceeding your cameras sync speed. Sure, you can use high-speed sync to achieve a similar effect, but just understanding flash duration allows you to do this without spending an arm and a leg on expensive strobes that support high-speed sync. I personally shoot with Paul C. Buff strobes which don’t have high-speed sync, but I was still able to create really awesome images of my dogs shaking off water after their bath by just understanding how flash duration effects the exposure of my image. Check out the above video where I explain flash duration in a little more detail.
[via Paul C Buff, Inc]