[BrianShaw]

Interesting, I didn't know the Speed Graphic didn't have an equivalent to the 35mm world's SLR flash sync speed, like 60, where the first curtain opens, syncs and then second curtain closes...

Lens shutters would solve that problem, certainly.

Graflex used a moving slit curtain. The slit was fixed sizes. It is one moving curtain, not two independent curtains.

Lens shutter solves the problem only if that shutter supports X-synch. Many, if not most, do but there were some shutters that did not have synch except that improvised using a solenoid... and that can't fake a X-synch.

EDIT: what Serius refers to as "O" setting on the Graflex focal plane shutter is FULLY OPEN - meaning the opening is 4 inches on a 4x5 camera. That is not a shutter speed setting, per se, but a way to keep the focal plan shutter curtain out of the way when using a lens shutter.