Originally Posted by nukecoke
I was checking on a lot of sample images from the J3+ when it was then newly out but I didn't see a BIG improvement (optically) over the old J3. There were also reports about miss-focusing from members on this forum if I remember correctly. Despite price difference, the obvious advantage of J3+ over old J3 is that it is a newly issued lens so it is less likely to be abused by many owners before the lens get passed on to you.
Lomography/KMZ also made the NEW Jupiter-9 back in 2013 but for some reasons they haven't brought it out yet. Maybe it is just a small amount of lens but I saw pictures of the lens on exhibition on some Russian forum, as well as a short description on KMZ's Jupiter-9 page
I didn't know there were focusing issues. I remember reading about user experiences here (RFF) and over at another Leica forum. Folks seemed genuinely happy with the performance. It still is a sonnar, so the focus shift didn't surprise anyone. I hear its really well built with better materials and precision than the original. Also better optical performance, mostly due to modern coatings and maybe better manufacturing tolerances. I seem to remember it has a click stop aperture ring (could be wrong about that) and (very important) it was built to the Leica focusing standard (and not the Zeiss standard as with the original). That seemed to be a big deal.
I seriously considered one, but eventually decided not to because I already have a nice original J-3 (1954) and an over-abundance of 50s. Right now, if I'd consider any 50 it would be an e46 summilux.
I also remember reading about a new Jupiter-9. Never heard anything more. I think that one would have
to be built to the Leica focusing standard to be of much attraction these days. Very few people seem to be successful re-shimming the J-9 for Leica type bodies. And even then, it is still a compromise solution.