I use a Canon EOS Digital Rebel XT with a step down adapter to fit my ancient 52mm Pentax Stereo Adapter (mirrors screwed onto the front of the lens). Very annoying to work with since it rotates when the lens focuses. The shadow down the middle of the pair is minimized at f4.5, so I don't have great depth of field, but depending on the shot, that's not a "bug", that's a "feature".

Canon T1i since 2009.08.22

Canon T3i since 2012.12.07

Note to self: big fotos only big 1600x2048 after 2012.03.01