What window? With high speed sync the flash overall duration has to span the curtain travel time (perhaps 1/300 sec.)Jerome,
As far as I can see this works with just Alien Bees and it's big brother. Also one would have to be sure that the flash duration fits into this window.
That is, the "high speed sync" mode (although that name isn't really all that descriptive either, since it isn't a special kind of sync but rather a special kind of output burst, although that does require a certain sync scheme)The solution to this, for example with a Canon flash, is to use it in the high frequency mode . . .
Indeed, thus my comment/question.. . . where multiple short pulses will illuminate the slit throughout it's travel. I can't imagine how one does this with an Alien Bee in slave mode! Does anyone know?