I'm pretty sure K bodies can do this, too. I once tested a KM, firing at a white wall using flash, from 1/60th to 1/1000, including guestimated half-stops. The shutter progressed smoothly in the sequenced photos, ie the guestimate 1/90 showed a little less shutter than 1/125, etc. I don't know if the K shutter is stepless below synch, though.
William Robb wrote:
The Nikon F2 shutter was able to give infinitely variable shutter speeds from it's sync speed up to it's top speed.
