Originally posted by doodlebug The mechanical bounce of the contacts and the inertia of the mechanical moving parts make mechanical systems unlikely to achieve timing accuracy better than 5 milliseconds.
Glad you made that point, because it is the physical location of both leading and trailing curtains that is critical for sync timing. X-sync accuracy is always in reference to the leading curtain clearing the image frame. There is a strong case for determining that event in real time rather than an off-set from the "start curtain travel" event. Whether this is done using contact points, feelers, reed switch, inductive pickup, or optical sensor makes little difference.
Steve
(...ignition and injection timing on my car's engine are coordinated from an inductive pickup on the cam shaft...)