Hi. I got a Metz 45CL-1 because the sun never shines around here, but now it is spring and I probably don't need it. I've never used a flash before. The instruc tions and the dial on the head have index for range and f-stop, but there is not hing for shutter speed. I'm using this on a 4X5 with lens in shutter that I unde rstand will flash at any speed. But what speed would I sit the shutter for, for a portrait? I'm sure there is something basic about this I just don't know, sorr y for asking what must be simple thing.