Friday, May 25, 2012
Flash Duration And Motion Blur
I teach a studio lighting class, and one of my favorite subjects is flash duration as it relates to exposure. (Because flash durations are so short, shutter speed doesn't affect them. Deep, I know. But trust me.) That always leads me into a discussion of how flash durations—while very, very brief—are still long enough to create motion blur on a fast-moving subject. Which then leads into a discussion about lowering a flash's output in order to shorten the flash duration in order to ultimately minimize the motion blur on the fast-moving subject. The DIY Photography blog now supports this thesis with visual evidence of a shorter flash duration and how it makes for sharper photographs, courtesy of photographer Sam McGuire. It also defies logic, though, because it is made with the Lumedyne 200w/s Action Pack flash unit. What's groundbreaking about this thing is that as flash output is increased, flash duration is decreased--a direct contradiction to the way this stuff usually works. But this is actually very helpful, since frequently more power is necessary in order to increase distance between flash and subject, or to be able to use light modifiers that more effectively shape the light. So the point of this post is two-fold: take a look at the DIY Photography blog to increase your understanding of how flash duration affects sharpness of moving objects, and then seriously consider the Lumedyne 200w/s Action Pack if you're serious about strobing sports action.