I want to see if we can identify the smaller rear lens element Jupiter 12's. To try and get a definitive measurement or list. They do exist as some people report they can mount their J12 on a non Zorki/Fed body without the rear lens element getting in the way. The problem is the knowledge of which ones is not known.
A couple of years ago one of the Russian sellers on ebay told me that LTM Jupiter 12's built between the years of x and y had a slightly smaller rear lens element so that they can fit in non Zorki/Fed cameras. Unfortunately I lost the bit of paper I wrote it on, and can't remember the seller now.
It's probably a bit simplistic to think that it will be all J12's between certain years too, more likely ones produced by certain factories at specific times.
So the idea of this thread is to try and find the answer. I'll also post it on the Beststuff Russian camera forum.
1. My idea is that everyone with a LTM J12 measures it's rear element somehow, especially the people with the ones we're looking for. How to measure- maybe just a piece of string around the rear lens element diameter? Then you can just lay it out next to a ruler and read off the diameter. Metric measurements in millimeters would be good as then we don't have to deal with that outdated 57/256ths of an inch etc...
2. Also the serial number of the lens
3. The factory that made the lens which you can find out here from looking at the logo on the lens:
4. Is it one of the smaller ones in your opinion i.e. does it fit okay on a Bessa/Canon etc...?
I think once we establish what the baseline is, that only people with the smaller than baseline ones should post as these are the 'mysterious' ones.
Any other ideas?