FotodioxLens Mount Adapter - Compatible with Black M42 (42mm x1 Thread Mount) Lens to Canon EOS (EF, EF-S) Mount D/SLR Cameras

Works like a charm on a RED cinema camera. I have the A-EF and the MD-EF adapters. Both of these adapters introduce new optics in order to make up for the flange distance issue (which would otherwise render the lenses unusable on EF.) The adapter optics introduce a touch of new character to the lenses. They introduce softness, highlight bloom, and halation when wide open. If you stop down a touch, they sharpen up while holding onto a tasteful dash of that character. The image is in my opinion very nice looking, and I might no longer consider using a filter in front of the lens to attain a similar effect. The character and overall look is in my opinion still clean enough to use on commercial work.

the only one that works great with my pentax takumar 50mm 1.4 lens. the V2 and other versions gave a stiffness to the focusing at infinity, whereas this one keeps the focus nice and fluid

This adapter suffers from a design flaw. I will get to in a minute which Nikon/EOS adapter to get.When I turn the focusing ring of a manual focus lens, or an autofocus lens functioning as a manual focus, I expect only the ring to move. With the Fotodiox there is excessive play (> 5 deg) between the lens and the adapter. When you turn the focusing ring with a Nikon AUTOfocus lens mounted, the lens will move first with respect to the adapter before the focusing ring does. I don't know about others but to me this is unacceptable. When I turn the focusing ring I expect only the ring to move. With AI-S (manual focus) lenses, the play is a little less (about 2 degrees), but in both cases there is not just rotational play between the lens and adapter which is hugely annoying but will probably not affect the final image, even worse, there is also a tiny bit of play in the angle the optical axis makes with the image plane. This *does* affect image quality as I have verified. Think 'view camera' where the plane of focus is not parallel to the image plane (sensor). At first I couldn't explain the loss of sharpness even with a stellar Nikon lens like the 17-35/2.8 on my 5d, but after some trial and error I pinned it down to misalignment between the focal plane and the sensor. This is simply not acceptable on any lens adapter regardless of cost.Now that we know what the flaw is, what to do? Well, it turns out are two generic Nikon/EOS adapter designs out there. Most importers (Fotodiox included) order these from China and put their own logo on it. I have an adapter *identical* to the Fotodiox that I got from eBay(tons of those out there) except it doesn't have the Fotodiox name. You can tell this design from the presence of a little black spring loaded lever that you press to unattach the lens from the adapter. This is the flawed design and the one to avoid.The other (costs about the same) has a little square tab with a hole in the middle which you push/pull to mount/ unmount the lens from the adapter. I own one of these as well. There is almost zero play with the lens mounted on this. It fits tightly and is a pleasure to focus with. This is the one to get. These are also plentifully available on eBay.Needless to say, my Fotodiox is going back to Amazon.

I purchased the Fotodiox standard Nikon F to Canon EOS adapter (model Nik-EF) because I have a number of older Nikon F lenses and wanted to play with them a bit with my Canon DSLR. While this adapter does work with Nikon F lenses, the fit is very, very tight. I tried it on 4 different lenses, all with the same very tight result. Tightness has the benefit of keeping it secure, but as a result of being so tight, you have to be very careful. And removing the adapter from the lens requires releasing the spring-loaded Nikon locking pin. When doing this, you need to be careful to ensure the release pin is not being stressed while unscrewing the adapter from the lens. You cannot starting twisting the adapter from the back of the lens before fully releasing the pin. The pin release lever is small and somewhat awkward to use. The entire pin release assembly does not strike me as robust and would be easy to damage by over-stressing. There is one review reporting problems with it. It certainly is not as well-built as the pin release button on a Nikon camera. This adapter is best suited for permanent adaptation of a lens rather than being frequently removed and installed on a different lenses. For $20, that could get to be pretty expensive. And, of course, you do not get any automatic functions. This is strictly for manual picture-taking. I would probably only invest the $20 for a very special Nikon lens and plan on leaving it permanently attached.Update 1: The one Nikon-F lens I have tried is a Micro-Nikkor 55mm f3.5 lens which normally focuses up to about 9.5". It is a very good lens for close-up work. The mechanical fit of this adapter is fine and using the Canon in manual mode is pretty easy. With the Canon, this lens focuses down to about 4" from the subject instead of 9.5". Unfortunately, this also means the infinity focus is fuzzy. This really is not the fault of the adapter, just a partial incompatibility between the lens and the camera. If you shoot at f32, the fuzziness is obviously less. At a wide open f3.5, my guesstimate is you can get sharp focus if you are not more than about 15' from the subject. So, this will still work as a good close-up lens, but that is it.Update 2: I also tried the Canon - M42 Type 2 adapter, which was just delivered. It is much easier to use than the Nikon F. I had some older Pentax-type screw on lenses from a Mamiya camera. These lens worked fine at infinity. The type 2 adapter is for lens with a diaphragm stop down pin on the rear. Again, there are no auto functions, so everything is in manual mode. I tried 35mm, 55mm, and 135mm lenses with the adapter. Of the three, I think the 135mm is the one I would likely use with the Canon camera. No reason to buy the pro model and from everything I have read, programming the focus chip is just too much effort and really is not necessary. Focusing through the viewfinder or screen is sufficient.