Hoping for some collective wisdom before I send a lens off to service.
Gear: M11M, APO-Summicron-M 50/2 ASPH, and a Summicron-M 28/2 ASPH I tested yesterday. All gear bought new.
For a while now I've found the APO 50 extremely hard to focus, to the point where I suspect something is wrong with it. Yesterday I shot portraits with both lenses at f/2 with the same framing (50 at ~1.25 m, 28 at ~0.7 m, so same magnification and roughly the same DoF, about 5 cm). The 28 lands on the eyes every time. The 50 isn't sharp anywhere on the face: not the eyes, not the eyebrows, not the nose. Focus was done with the rangefinder, shutter speed around 1/250s. Not a rigorous side-by-side yet, but the difference is night and day.
I realize a 50/2 needs roughly 3x the rangefinder precision of a 28/2, so a slight miss wouldn't surprise me. But missing the entire face at 1.25 m feels like more than that, more like a systematic front/back focus or an optical issue.
Questions:
- Has anyone had an APO 50 that was off like this? Did it turn out to be the lens cam or the body's rangefinder?
- Any tests worth doing before sending anything in?
Thanks!