Originally Posted by
DavidEccleston
The part of this that is confusing is that we know from HSS requirements for the flash that for a shutter speed over 1/250s, the shutter open and shutter close overlap. You need multiple rapid flashes to illuminate the subject while the two shutter curtain moves and different parts of the sensor are receiving light... which means any shutter speed over 1/250s technically should have the same rolling shutter effect. With flash and low ambient light you might even expect to get multiple distinct chunks for each flash exposure as opposed to the continuous jello look you get from slow readout.
I'm not invested enough to bother doing any experiments though, and a quick google search didn't reveal anything interesting. All the links talking about shutter curtains are about 2nd curtain sync flash timing to get trails, not anyone talking about artifacts.