does anyone know the voltage for a vivitar 550fd ? we have two of these hot shoe flashes, that we bought for our film camera's. it seems i often saw threads about using flashes with too high of voltage, on dslr's now that we have our dslr's, i'm scared to test the flashes. i have the manual, but can't seem to find anything about voltage or trigger voltage. is anyon familiar with these? camera's are Canon 450d/XSi and flashes are Vivitar 550fd thanks!