I have had very good results using a Vivitar 550FD Flash unit with my Rolleiflex E2. Using Ilford Delta 100, I set the f/s to 4 and I think I set the shutter speed to 1/60. This is where my question comes in. Because I have failed to keep a journal (I'm going to for now on), I cannot remember if that is the shutter speed I used and where I learned that this is a good shutter speed for using with the flash. Is 1/60 a good shutter speed to use under these conditions?