Seeing what’s possible when you stop fast moving motion is always very cool because you view a snippet of time that happened in a split second. The best way to do this isn’t necessarily by using a super flash shutter speed but instead by using a flash with a fast flash duration.
Gavin Hoey at AdoramaTV tries to demonstrate this in a very educational video that shows off what happens when you try to shoot a scene without the flash, with the flash, and without any ambient light in the scene. Gavin builds up cumutaviely and shows you how lower flash power usually means a faster flash duration because the flash has to fire at a faster duration.
So how does flash duration works? In lay man’s terms, what it basically does is take over characteristics of the shutter speed. If you’re shooting with a two second long exposure, the scene will let in that amount of light but when you use it with a flash that has a flash duration of something like 1/3200, it will stop the motion in the same way that the shutter would if it fired at 1/3200.
As far as your aperture or ISO goes, all that does is control the amount of light from the flash that actually affects the scene and the overall sensitivity to the light. This is part of the idea behind an item like the Triggertrap flash attachment.
The video on high speed flash photography is very fun, and you should check it out after the jump.