Isn’t that precisely what is suggested by the title?

Also, this isn’t any “adapter”:

> My friend, a Russian lens technician, who loves nothing more than to frankenstein equipment [...] called me into his store in NYC. [...] He found in a box of random parts, hidden inside anther lens this gem. A circa 1908 (possibly earlier) 35mm lens. Still functioning, mostly brass, and not nearly as much dust or fungus as one would think after sitting in a box for over a hundred years. This lens is a piece of film history people, and at this point rare beyond words. So i say to him, “Wow... what do you have in mind?” He smiles, and says (in the thickest Russian accent you can imagine) “I can make this fit EF you know....” My eye twinkled, and then 6 nail-biting hours later, he had it finished. My Russian lens technician is a mad scientist and he took what sounded like an angle grinder to the lens to make it clear the flange distance and the mirror.... This lens’s value is unclear. It’s sort of on loan. It’s the only lens of its kind on a 5D... or any digital for that matter.

T-mount beats F-mount by 2 years. It's not as elegant as F-mount, but it's very simple - essentially a screw.

I use it with adapter to attach my Nikon DSLR to a telescope.

There is some astigmatic aberration as well as vignetting visible in the photos provided, but it's possible that this lens was intended for a smaller image circle than 24x36 sensor in the 5DmkII. All lenses will have astigmatic aberration and vignetting at the edge of their image circle (which is normally outside the photographic media the image is being projected onto).

This lens is uncoated and highly susceptible to lens flare. As I understand it, many lenses before the 4-element Zeiss Tessar also tend to have more pronounced flare than later lens formulas. You can really see this in some of the photos.

Overall, it's neat little lens and I would shoot it in a heartbeat. It looks very sharp in the center with gentle fall-off near the edges. The owner could go a long way to get the most out of it by crafting a little lens hood for it -- it really helps with older lenses like this.

Visually, coated lenses yield more contrast. In the case of more modern (usually after the 70's) multi-coated lenses, there is also a UV-reducing layer that maintains more detail at a distances due to minimized haziness.

Some of my favorite examples of a classic, uncoated lens showing its effect are from the Lewis Hines photos of the Empire State Building construction.

http://en.wikipedia.org/wiki/File:Old_timer_structural_worke...

There is some obvious dodging and burning done to this print in particular (the worker has been darkened compared with the cityscape in the background) but notice how much the detail fades with distance.

This person stumbled upon a 100+ year-old cinema lens and thought to adapt it to a modern DSLR, take some excellent pictures with a wonderful vintage feel, and post them online for all of us to share. I would most certainly call that unusual.

Let's give credit where credit is due. This is a wonderful and novel piece of work and I'm definitely grateful that s/he chose to share it with us.

http://en.wikipedia.org/wiki/M39_lens_mount

You could start with a T-mount adapter to get to 42mm:

http://en.wikipedia.org/wiki/T-mount

http://www.adorama.com/LNTMEOS.html

Then a 42mm to 39mm step-down adapter ring:

http://www.amazon.com/Fotodiox-M39-Adapter-Zeiss-Pentax/dp/B...

Not sure about the clearances, and you may not get infinity focus depending upon how far out the lens ends up being situated from the focal plane of the sensor.

Edited to add: google turned up this direct EOS to M39 adapter:

  http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=110365260908&ssPageName=STRK