Originally Posted by jamais
Great! I might have misunderstood the information in the quotation above.
I would consider that post you referenced an opinion more than information.
I own and use several FSU lenses on my Bessa cameras--I have an R and an R2A--and most of the lenses I own were fine when I got them.
I did have to have two adjusted. My J-9 and my J-3. That was more an issue of previous mistreatment than the design. And those two have very shallow DOF at wide apertures and close distance.
If you want to use the FSU lenses on Bessa/Leica/Zeiss Ikon/Canon it would make better sense, I think, to adjust the lenses if needed
rather than the camera body; if you adjust the camera, then you are likely to have focus issues with the vast majority of Leica, CV, Nikon, Canon, etc lenses.
The focus issue with FSU lenses and Leica standard bodies is real but not, I think, a huge problem with most FSU lenses. Mainly because the slower lenses seem to have enough depth of field at their widest apertures to cover the focus error.
As well, the two lenses that seem to give the most trouble--the 85mm/f2 Jupiter 9 and the 50mm/f1.5 Jupiter 3--do work well once correctly adjusted.
The more usual lenses--the various 50mm/f3.5 (Industar 10, 22, or 50), the Industar 26 or 61 (f/2.8), and the 135mm/f4 Jupiter 11 haven't given me any focus trouble on my cameras. I did try to get well working examples and I think I've been sucessful.
The Jupiter 12, 35mm/f2.8 is has a different problem with the Bessa bodies: the rear of the lens protrudes too much into the camera body and will at least block the meter cell and may well interfere with the shutter blinds.
Explore the FSU forum here and you will find lots of info and opinions about using these lenses on modern bodies.