Ambro51
Collector/Photographer
When I built up UR Leica to “working”, I searched for, and found, Barnacks initial trial optic. He used the same lens that was on the movie camera, the Zeiss Kino Tessar f 3.5 5cm. This was the fastest Tessar lens of that size, and exclusive to Cine Cameras. The of Style lettering and serial number date it to 1911. Amazingly, the lens threaded right into the UR barrel, and when that inner barrel was retracted to the lip of the outer barrel, the camera was in perfect focus!!