Quote Originally Posted by Dan Fromm View Post
Not how I'd do it but it might work if you can get rings with the appropriate threads and if everything is very tight so that the rings are loaded only in tension.
Dan, the only way to mount Rodagon-G 210 M72 lens on Copal #3 seems to be screwing it to the shutter's front thread, which is recessed about 6 mm. I do have a high-quality M58-M72 0.75 step-up adapter with threads longer than those usually found on Chinese adapters. But it's outer diameter is larger than the front opening of #3 shutter and I'd need an approx. 10 mm M58 extension ring of comparable quality and thread length. The only such ring I know of is a really expensive Schneider extension tube for Unifoc system, and I don't know if the threads are long enough to have everything tight. Or did you perhaps have a totally different idea for mounting a M72 lens in front of a Copal #3?