Quote Originally Posted by octofish View Post
Hi. To OP (or anyone else with any ideas) - I have an opemus 5 and just bought a rodenstock rodagon 2.8 50mm for it as well. The M39 thread fits fine, but the actual case of the lens hits the rounded recessed part of the standard opemus lens board when you try to attach it in the inverted position necessary to get focus in 50mm and so it seemingly cannot be mounted.

Did you get this to work? I am struggling to work out what to do short of getting a custom lens board made up, if that's even feasible.

Really annoyed actually cause it seems like a great lens!
I ran in this problem years ago, too, "big" enlarging lenses cannot be fitted into the reversed board, because of its "bell" shape. The solution is to use a "plan' lens board, and then, the lens is closer enough to get proper focus. I have to check it, but I believe I recycled a Durst lens board for this on my Opemus. If you have a retaining ring for M39, your plan lens board don't even need to be threaded.

Best regards,