I was a Kickstarter backer and my Phochron XA shutter speed tester arrived last week. I found it really easy to use and seems like an all around great tool for those of us who shoot old film cameras. (NB: I have no affiliation with this product) It was a bit of an eye opener testing some of my shutters. knew that my Nikkor-W 135mm was having shutter issues but I really didn't know how bad it was until I tested them. Basically none of the speeds are reliable. I also found out that my Mamiya C330 80mm lens is consistently a stop slow. Both of those shutters are now on their way to get serviced. Fortunately the rest of my Copal large format shutters checked out.