[scollins]

Originally Posted by rodi

I started typing a bunch of explanations and it was getting lengthy, then I found this:
http://nikonclspracticalguide.blogsp...explained.html

Basically, you're stretching the output of your SB flash across a longer duration so that the small slit of the sensor exposure that moves down the sensor for a high speed shutter gets the same amount of light exposure. otherwise, only part of your sensor (in a horizontal slit) will be exposed to that light.
In order to stretch the time, the power output is reduced. So you'd have to have the light pretty close to your subject. And if you have something to diffuse it, you're reducing the power even more.

I guess test it out?

Thanks for that link! That explains a lot. I did try it out and I noticed that the flash power was pretty weak (with 1/4000th anyway.) I think stepping up to the SB-900 would help, but based on some of the comments in that link, 1/1000th to 1/1600th is about the practical limit for usability.

Still, I'm pretty impressed that Nikon was able to somewhat "fudge" a high speed shutter sync. I'm guessing it will only work with Nikon Speedlights, since most studio flashes seem to have very fast durations, and I don't know if they can be changed.