I wrote > I think many cameras will have perhaps 30ms from trigger to exposure > and the only way to catch the actual event would be with the shutter pre- > opened (and a front curtain flash if necessary) Oooops. Front curtain flash goes off when the shutter opens. The shutter is already open, the flash would be triggered by the event -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist