I have test shutters with clocks, lathe and motor just by taking a photo this is not hard to do. Most motor on no load run at 1800 or 3600 rpm does good job for high speeds. I was telling a member early this month on how to do this check. for slow speed check I use a lathe on slow speed it to has a known rpm. Clock is same way. Use a bright light a flash will NOT WORK

Dave


[This is off the
http://tech.groups.yahoo.com/group/c.../message/30439

If you can find a 78 rpm record player and record, your problem would be solved by seeing how many degrees a white line from the center point of the record traveled while the shutter was open.]