Prototype / Home Made Lens - Help me learn more about this?

nhfoley · Joined: 04 Aug 2013 Posts: 3 Location: United States

I bought this lens on eBay a few years ago. It was described as a prototype macro lens of unknown origin. When I got it in the mail, it seemed to be more like someone's home-made lens - maybe a machinist, because the entire thing is decently machined out of brass & aluminum, and then painted like a shop tool. It has one large helicoid, and the entire optical cell extends to go from normal to macro mode. There is no aperture, and it looks like the optical design reflects that - ie there are only a few elements. It has a canon EF mount, clearly pulled from some other lens. It seems to be about 65mm focal length (it's a bit narrower than my 55mm, and wider than my 85mm), and the fixed aperture seems to be in the f2.8-4 range just based on the physical size of the thing. The optics seem old - there are some small scratches (unremarkable) and a fairly high number of bubbles in the glass.

It's sat on the shelf for years - I took a few pictures with it and saw it as an interesting novelty. I dusted it off today and put it on my camera (Sony A7) and shot some photos as I went about my day. The results were pretty striking. It is very sharp, has surprisingly good bokeh, and CA is extremely well controlled. It vignettes some on full frame, but not enough to ruin photos:

Macro mode is also pretty stellar, even though the DOF is paper-thin without the ability to stop down:

There is a larger album of photos here on flickr:
https://www.flickr.com/photos/nhfoley/sets/72157650950466382

So, does anyone here have any insights as to what this lens is? Some sort of homebrew body for an APO enlarger lens? a prototype of something? hacked optics from a larger format system?