Karat-Xenar 5cm F2.8, hacked into Leica Mount.

[Brian Sweeney]

Schneider Karat-Xenar 5cm F2.8 from last week's Photorama show, loose lens/ no body. $30, Hacked into Leica Mount using the focus mount from a Canon 50/2.8 (unuseable glass on the canon, etching). The Karat-Xenar is a 5-element in 4 group lens. Looks like it is based on the Tessar, but uses an air-spaced doublet for the front section. It is much sharper than my Zeiss 5cm F2.8 Tessar of the same period, 1930s.

Turns out the threads on the lens are the same as the retaining rings on the I-61, and the retaining ring of the Canon is close. I used a little teflon tape made for pipe fittings to secure. The trim ring on the filed-down Canon barrel is from a parts Kodak TLR. The split ring from the I-61 is used as a variable-stand-off to calibrate the lens for correct focus.






Lots of filing and testing using a TTL viewer.

Was it worth the trouble???

[Brian Sweeney]

This is a fully-coated lens, WW-II vintage.



A good candidate for hacking as the lens and aperture is on one piece, and simply unscrews from the Karat body. Much easier than converting a Retina-Xenar, which has a between-lens shutter.

[joho35mm]

Wow! This is amazing stuff, technically and image-wise. How did you decide on this lens to convert, and how much time did it take for you to figure out all the separate parts to put together? I have very little mechanical expertise, so I would've considered this one of those "in-your-dreams" kind of task.

[Brian Sweeney]

Found the lens at last week's Photorama, same dealer with the $10 CZJ Tessar 5cm F3.5. Asked about this one and got, "Ohh. That one is expensive, $30." It formed an image, so it was complete. Almost any 50mm lens can be hacked into Leica mount if it is one piece construction, and has the aperture with aperture ring built into it.

Got it home, took it apart to clean up the surfaces. Sat with the box of parts from junk lenses and left-overs, just like tinker-toys. Something is bound to fit together, a lot of lenses used standard threads sizes. This one matched the I-61 retaining rings, and the Canon 50/2.8 retaining ring happened to screw into them. the worst part was making the cover for the 50/2.8 mount, again back to the "big box of junk parts". The Kodak TLR ring was the right size, had to file off the inner ring so the aperture of the Xenar could be reached.

[Raid Amin]

The lens looks cool, Brian, and it can perform well too. Such one of a kind lenses are lots of fun and they can make photography more enjoyful.

Raid

[br1078lum]

Was looking at Mercury II's on eBay, and came across one where someone had hacked a Tessar onto it.  He had to do some grinding on one of the rings to get it to clear the front knobs.

PF

[radiophoto]

Very clever, Brian, and from the results I'd say it was worth the effort.