Originally posted by kenyee If you're freezing motion w/ sync speed, you don't understand strobes...
Not true at all.
Not all strobe photography is done in a dark room. When shooting action sports outside, you are typically mixing strobes with the constant ambient light. Let's say you're shooting BMX people do backflips, since this is a situation that's I've particularly had trouble with. It's the golden hour and sunset looks good. You want to drop down the ambient light a stop or two, so everything get nice and rich, but not so far that everything goes black. Then you want to add light back in on the BMXer. Problem is, they're moving really fast while they're doing that backflip, and since the constant, ambient light is still part of the exposure, the BMXer is going too fast for 1/180th.
What you end up with is almost a double frame, two seperate exposures. You get a nice sharp image of the BMXer from the flash, but you also have a blurry, ghosted image of the BMXer underneath the sharp one, and makes the whole BMXer look soft. The difference in motion blur from 1/180th to 1/250th is more than you would think, and it makes a big difference in these situations. The only thing you can do otherwise is stop down the ambient light so much that it's not a factor, which a) kills the ambience of the sunset and the golden hour scene, and b) requires huge amounts of watt/seconds.