The biggest things to keep in mind with the Synchro Rapid 800 shutter are, first, don't expect the 800 speed to be accurate -- it's probably more like 1/500, with the 400 around 1/250 and 200 between 1/125 and 1/150, if it's like others of that breed I've read about. Second, never, EVER set the shutter into highest speed while cocked. The force required to compress the booster spring can be enough to break something -- and as suggested above, if you break something, it can't be repaired.