Wanted to buy: 500mm f/3.5

Why have I not heard of this lens before?
(although now I have, because for 3 works into my new job i've been paid to sit around and do nothing while I wait for a license to the program I need, why not look up lenses?)

http://www.zenitcamera.com/archive/l...ith-camera.jpg
ТОЗ-500 (TOZ-500), probably the biggest and fastest mirror-lens ever made (besides telescopes, although honestly I can't see what the difference is).
Weird thing is, it was made only in M39, which is the Leica Rangefider screw-mount, not only is there no rangefiders for 500mm lenses, by the looks of it the rangefinder would just point at the back of the lens.
Or it could have been made in the M39 Zenit-SLR mount, same as Leica screwmount but infinity-focus at a flange distance of 46mm or so, so it would actually hit infinity on almost any SLR except nikons.

Worst part is, it looks like only a handful of prototypes were ever made, so there's probably as many in the wild as there are EF 1200 f/5.6 Ls.

If anyone ever sees one, be a dear and let me know...