I am having trouble with my Summicron after I had it serviced together with my M2.
The M2 received a CLA, it seems fine. The lens had an oily dust-speck that was removed, the aperture blades were cleaned.
After I received it back, I noticed that the rangefinder patch does not align at infinity. It focuses short, not beyond infinity. I did not try the moon, but if it falls short on targets 2-3 miles away, it should also fall short with the moon. Also I noticed that the resistance of the otherwise smooth focusing ring felt a little uneven near infinity. A little 'scratchy' maybe.
I tested the lens on another body (M6) and compared it to other lenses. The alignment issue was the same on both cameras, and other lenses moved the rangefinder into proper alignment on both cameras. I did not take photos with both cameras. Just checked rangefinder alignment. What I take from this test is that it must be the lens cam and not the rangefinder of the M2 that is off.
I asked my service man (supposedly a reputable guy here in Berlin) about it. He said he only cleaned the optics, and hadn't touched the focusing helicoid. And he said he tested the focus scale for accuracy, finding no issues with the lens. i.e. the distance scale indicates the correct focusing distances.
After closer (re-)inspection he proceeded to claim that the lens cam that moves the rangefinder had been ground down, possibly by a former owner or unskilled repairman. I took this for the truth and went home, devastated because my lens was possibly beyond repair (apparently replacing the cam is something only Leitz can do, he won't get the parts. And a proper Leitz service would be more expensive than buying another used Summicron 50 v3.)
I then compared the lens cam of the Summicron with other Leitz lenses I currently possess. They all look very similar, the brass of the cam is ever so slightly carved down in the area where the rangefinder arm touches the cam surface. The surface is never 100% even/flush. I hope you understand what I am trying to describe here, I have put some macro images of the rangefinder cam in an imgur album. All of these are images of the same lens, the Summicron.
Anyway, with that being the case, his theory on why the rangefinder was off should not be true.
My initial fear was that if the whole focusing mechanism was off, I'd over-compensate at all distances and focus past my subject to see proper alignment in the viewfinder. But my test images do not seem to indicate such behavior.
I have done some test shots between minimum focusing distance and two meters, and some in the 30 to 50m range and then about 5 km away at f5.6. All shot on APX100. See images attached. It seems fine at close and medium distances. With long distances it’s a little harder to tell; the day was a bit foggy. But to my eye, it does look washed out and not sharp at the subject (the tv tower in the far background) at proper infinity. Instead, the focus seems to be on the lanterns at medium distance.
I could test the lens on my digital Fuji using my cheap M adapter, but I do not trust these adapters. I have read that they often have a slightly short flange distance in order to ensure proper infinity focus.
My current theory is that the cam itself is fine, and that the lens does focus correctly according to its scale. The reason for the misalignment in the viewfinder at infinity and the sub-optimal sharpness at far distances would then be caused by a premature stop of the focus ring. Thus, the lens simply never reaches true infinity. This could be correlated to the slightly 'off' feeling of the focusing ring when approaching infinity. Also, as seen on the last image in my album, the focus indicator on the distance scale seems to stay a little to the left of the infinity mark.
Have you experienced similar issues with a rangefinder lens?
Do you see any issues with the rf cam?
What ways are there to further narrow down the issue?
Do my analysis of the issue and the conclusion that I draw make sense?
Is it possible that the lens helicoid stops turning before it reaches infinity?
My mistake in all of this: I have not thoroughly tested the lens before handing it in for cleaning. I am quite sure that the rangefinder alignment at infinity had been better before and I cannot recall the slight change of turning resistance toward infinity. But I did not consciously check and take notes. Lesson learned!
Should I enforce my warranty rights and have him take it apart again?
I do not want to do him injustice, since I am not 100% certain of the condition of the lens before repair. At the same time I have lost faith in his judgement to a certain extent after his comment regarding the supposed damage of the lens cam. Also, he also did not do his best work on the aperture ring, as at first the front ring was loose, and then, after tightening, the dot indicating the selected aperture is off to the left. See images. Not very convincing.