Quote Originally Posted by Neal Chaves View Post
You have an X sync shutter. Aim the strobe to light up a wall with the strobe. Hold the lens in your hand and look through it at the wall while you trip the shutter 1/60 sec. at wide open aperture. If the strobe syncs correctly, your eye will retain an image of the shutter blade position at the instant of strobe burst. The shutter blades should be seen wide open. If not, you have a shutter problem.
Do it at any speed. A properly synced shutter and flash will result in a bright white circle. It is best to do this at a high shutter speed as synch is more critical there then at low or middle speeds.