I was contemplating two recent acquisitions, an Argus M21 Markfinder and an Argus C-four with Geiss modified lens mount. Both cameras were rather rough.
The M21 was late production, the C-four early, so many parts were similar. Both cameras needed a teardown and rebuild, which led to a plan to combine the two cameras and swap out the lens mounting systems, just to see if I could.
The first result was a Model M21 with Geiss modified lens mount, ready for C-four Geiss mount lenses. I have never seen one, have you?
The rebuild was not easy, many internal parts of the two cameras had differences to overcome.
The 100 mm Tele-Lithagon lens came in the box with the C-four. It was also rough, and needed internal optics cleaning. The focus was completely off, and had to be calibrated from scratch.

With the first "Monster" ready for field testing, I loaded a roll of Kodak 200 and headed down to the Meramec River across from Old Town Fenton.
It was cold, and numbing whenever I removed my gloves to shoot.
A few image pairs below show results with both the 50mm Cintar and the 100mm Lithagon. I thought the 100mm was a bit soft in the corners.
Like with many M21 examples, the film got shredded at the end, as you can see.

Please click on thumbnails to enlarged.
All images are ©2020 E.J.Kowalski.
Thanks! Ed