kmz_j3_1950_1 by
fiftyonepointsix, on Flickr
kmz_j3_1950_new_mount by
fiftyonepointsix, on Flickr
a 1950 KMZ Jupiter-3, made in Germany in 1945, and made fit for use by me. The focal length was too short to focus in the original Contax mount, the threads were mismatced, sewing thread used to hold it in. Glass set in a new fixture, modified to Leica standard focal length and set in a Leica focus mount.
I understand about being caught up in variations of lenses. I have a "Fifty-Fifty" collection of Sonnar formula lenses that span from 1934 through to 2016, made by Carl Zeiss Jena, Zeiss Opton, Zeiss/Cosina, Nikon, Canon, Tanack, KMZ, ZOMZ, Valdai, Walz, and now Zenit. Thirty 5cm/50mm in Leica mount alone.