Sure looks like a range finder lens. I concur with the M39 thread. If you have a M42 adapter you may try to screw it in and see if it fits. What a cute little bugger!
Agree, looks like LTM (leica thread mount), esp. given how far back the helicoid sticks back from the mount surface (e.g. short backfocus register distance) so more than likely rangefinder lens for sure.
Paul Yi wrote:
Again, mount conversion/modification is out of question?
You could physically mount the lens on an EOS camera, but you would be unable to achieve infinity focus, only good for close-up work.
I believe the new micro 4/3rds cameras have mounts becoming available for Leica Screw Mount lenses, the register distance of that mount will allow infinity focus with a Leica screw mount or Leica M mount lens.