Just Fred wrote:
I think rjaywallace has it right. According to the D7100 manual (yes, I have one, too), on page 337:
Shutter
Type: Electronically-controlled vertical-travel focal-plane shutter
Speed: 1/8000 - 30 s in steps of 1/3 or 1/2 EV, bulb, time, X250
Flash sync speed: X=1/250 s; synchronize with shutter at 1/320 s or slower (flash range drops at speeds between 1/250 and 1/320 s)