Originally Posted by polyglot
M39 to M42 adapter would give you lots more options, maybe including a camera you already own.
The m39 I have is for rangefinders with a shorter distance to film plane
m39 for Zenit SLR's would work on my 5D, and I have an EOS adapter but it's great for macro work as I only have 1' of usuable distance.
5x7 Eastman-Kodak kit / Meyer Gorlitz 13.5cm/4,5 Trioplan / Bausch & Lomb Zeiss-Tessar 5x8 f4.5
Mamiya 645 / 150 f3.5 N, WLF, metered prism finder, left grip
FED-2 / 50 2.8 Industar 26m / 85/2 Jupiter-9
Canon 300v / 5D d*****l / L lenses