I have been able to focus both the CV 75/2.5 and the Tele-Elmarit 90/2.8 on my R2A without problems, despite my aging eyes. I hunt a bit wide open and close-up once in awhile, but I attribute this to myself not the camera. I tried a new 90 Elmar inside a local shop and it seemed to focus fine. I can't say the same for a new 90 Summicron that I tried at the same place, which involved a lot of hunting and uncertainty. Close and wide open, those extra 2 stops seem to pose an problem. I think you'll be fine with the Elmar.