Yesterday I ran across this old German made lens (maybe 1950's?) in my box of broken stuff and abandoned projects.
Purchased years ago, it was never used by me because the aperture ring is frozen solid and the focus does not work correctly. There is also some coating damage.
Focal length is 100mm.
Mounting threads are m42 Universal Screwmount.
Curious as to what the original capabilites of this lens might have been, I decided to try a little adapting.
Partial disassembly allowed me to access the aperture blades, so I manually set the blades to what I calculated as about f/8, cleaned the glass, and reassembled.
With a Screwmount to Pentax K Mount adapter, and a short K Mount extension tube, I was able to mount it to a Pentax K100 digital body.
With just the mount adapter, I could focus to approximately 50 feet.
With the addition of the extension tube, the focus changed to just a few feet.
Camera body set to AV Mode and ASA 800, I looked for subjects around the house. All hand held and available light.
Yes it worked. A little gentle tweaking, and I think some of these images are not so bad.
Even though the mechanics of the lens do not function anymore, I think the makers did something right with the optics.

Please click on thumbnails to see enlarged.
All images are Copyright 2015 E.J.Kowalski.
Thanks! Ed