Now that I got a Mamiya RB67 & a C220 I'm wondering how I can use electronic flash with these beasts? Can I shoot at 1/60 or 1/125 as if I was shooting with a 35mm SLR? Do I use the same f stop (depending on the distance) the my flash says, no matter what shutter speed I use? I plan on using a Sunpak Auto 522.
Basically you use what speed you want. Only two times to worry about shutter speed. Check how long your flash runs at full power. The other time is dragging the shutter. Any thing else is totally up to you.
Nick is correct, the flash duration is much shorter than the fastest shutter speed you have. With 35mm or any camera that uses a focal-plane shutter the limitation is the time the shutter blinds are completely open.
Yup the x-sync fires when the shutter is fully open so regardless of shutter speed, the flash always fires at correct point so it synchronises on all shutter speeds unless maybe you have shutter speed greater than 1000th second which could be shorter than the flash duration but depends on the flash unit and how much output it is giving.
Two good things about leaf shutters on interchangeable lens cameras (1) There ideal to to use for fill in flash to balance the ambient light with the flash, because you're not limited to a single shutter speed as you are on focal plane shutters. (2) If the flash sync on your lens packs up and won't fire your flash you just use another lens.