|Posted: Mon Jan 17, 2022 2:21 am Post subject:
|I've got a Karat Xenar coated, wartime, that turned out to be the 5 element design. This is not the same optical formula as the pre-war (or post-war) 5cm F2.8 Xenon. I also converted a pre-war 5cm F2.8 Xenon to Leica mount, and had to replace the front element with one that I still have. The latter- a Retina-Xenon 5cm F2.8 uncoated lens, converted to C-Mount.
The Post-War 5cm F2.8 Xenon is a standard 1-2-2-1 configuration, has a truncated front section. The back section is the same as the 5cm F2 Xenon, at least true in my Retina IIC and IIIC.
The Super-Xenar is basically a Tessar formula lens where the front element is split into two elements of lesser power, are closely spaced. The postwar Xenars of the Retina line went back to four elements, must have had better glass available.
The front section of the pre-war Retina 5cm F2.8 is very different from the 5-element Xenar, the underside of the front element is flat. The front group is mounted in a brass fixture, does not separate. Not sure if it is a cemented pair, or air-spaced doublel. On the Xenar the front fixtures all come apart and you can get to all three elements. The rear fixture- I cannot get to it. Maybe I'll buy a pre-war Retina II.