This lens was probably involved in a war... judging by the condition of metal parts.
The back end was wobbly, and one of the critical parts (aluminium cast, the part that had threaded holes for flange) was partly broken, but I could not make the new one for various reasons, one of them was I wanted to keep the iris mechanism in original condition and functionality). So I compromised here a bit....
Also, those lenses have back end that could be rotated (in increments of 90°), and the part that rotates was hit (or lens landed on it with it's full weight of 5.5kg), resulting in damage at the inside rim, which was visible as slight thickening at the end of the tube).
I repaired this on lathe by removing 0.3mm or so, but I am not sure the cut was done with enough precision (when I tightened the part in the chuck, I didn't remove the paint from the tube, so there was a possibility of some introduced eccentricity and/or non-orthogonality).
Quote:
Originally Posted by JA
It would be good as a "quick" reversible test or even possible fix
Bojan, I'm not quite sure what you mean I wasn't referring to any outdoor tests, but possibly inside on a bench.
One thing is for sure, you need to fix it in the way you described initially- fix/adjust the camera, then fix/adjust lens separetly, BUT before ANY of that I would test the situation with different lenses to see if the issue is still present.
You mentioned your 400mm 2.8 was an FD modified to EOS mount. In modifying an FD lens to an EOS mount isn't there a lens mount flange to focal plane difference that needs to be accommodated in the modification - 1.5-2 mm or something? If that isn't perfect perhaps that causes a slight difference in the corner focus vs centre focus due to the flat film plane vs spherical surface (however slight) of the light wave, causing problems with infinity focus. Maybe that 1.5mm-2mm difference should be checked or what's the word from Bridge, ....finessed?
Best
JA
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