Paired with a DSLR, this lens increases horizontal field of view by 1.5x. The aspect ratio, when properly unsqueezed is no longer 16:9, instead 2.35:1, which is closer to true widescreen cinema. Produces pleasing anamorphic flares, oval bokeh. These vintage lenses have been "adapted" to fit on DSLR lenses for anamorphic shooting and are incredibly hard to find.
Rear thread is 24mm. Lens is quite small. Minimum focusing distance of 2.5 feet. Maximum focusing to infinity. Sharp through all apertures. Requires focusing on both this lens and taking lens.
Optically it is in next to mint condition. Few dust fragments inside, however they don't affect video quality whatsoever. No fungus, gas, cracks, or scratches. Cosmetically minimal signs of wear on the outside. Comes with lens hood, and original miscellaneous equipment. Only front cap. No rear cap.
On crop sensor cameras (7D, T2i, GH2, etc.) widest lens you can use is 50mm. Any wider and you get vignetting. On full frame sensors I think you have to use 85 or longer to avoid vignetting.
Used mainly on a Lumix GH2 micro 4/3 sensor with different 38, 50, 85mm primes. If you love the look of authentic widescreen ratio this is one of the best tools to give you that.
Search Vimeo for "bolex moller anamorphic" and for some amazing results this lens can do.
Bolex Moller is prized among the top, if not the best anamorphots. I paid $1600 over year ago for this (without a clamp).
BONUS:
I'm including a Vid Atlantic anamorphic clamp (See photos). This clamp screws onto your taking lens just like a filter. It has a rear thread of 60mm. Comes with 2 step up rings. 52-60mm and 58-60mm. You can, of course attach more to make your taking lens fit.