[Dewman]

Where can I find out about the lens mounting system commonality? If this seems like a "stupid question," I'll have to live with it....but, for instance.....will Canon lenses work with a ME Super?

Thanks for any information you can provide.
Dewman (The new guy)

[Blue]

No, a Canon lens regardless if its an FD or EOS will not work on anything with a k-mount whether it is a ME Super or K-5 dSLR. The mounts are a different type and diameter. Plus, they have a shorter registration distance than the Pentax. If you are into vintage Canon FD glass, it won't work on Canon EOS either with a couple of rare exceptions.

[calsan]

A 4/3 camera would allow that with the right adapters. I saw a guy using his lumix camera and a really old manual focus 400 2.8 Canon lens at an Astronomy show (an equivalent of a 800mm 2.8 lens!) The camera looked like a lens cap on the end of that huge lens.
I presume the Pentax Q would be adaptable also for "off the dial" telephoto options.
You just won't get a wide angle option with the above cameras.

[RioRico]

There are two issues here: the lens flange-focal-distance aka register (distance from lens mount to film or sensor frame), and the mount mechanics.

* REGISTER: Longer-register lenses can be used on shorter-register cameras with non-optical adapters, and can focus to infinity. Shorter-register lenses on longer-register cameras can only reach infinity focus using optical adapters that change the lens characteristics. Some relative registers, from longer to shorter:

Nikon > Olympus OM > Pentax PK/M42 > Sony-Minolta Alpha > Canon EOS > Minolta MD > Canon FD > Leica M/LTM > m4/3 > Sony NEX > Pentax Q

* MOUNT: Some lens systems use very similar physical bayonet mounts, and with fairly close registers, it's not hard to mod Nikon, Olympus OM, and Yashica C/Y lenses to Pentax PK. Canon FD is a breech-lock system; I'm not familiar with Canon EOS; but these are NOT easy to mod, and the physical structures of the lens bases just aren't amenable to re-engineering. Minolta (Alpha and MD) are similarly beyond the range of possibility.
________________________________________

I have modded Nikon, OM, C/Y, and Petri bayonet mounts to PK. (The Petri mod is non-trivial.) I have adapted Exakta and Argus mount lenses. I just *might* be able to mod a Pentacon Bayonet. But ain't no way I'm messing with Canon, Minolta, Konica, Fujica, etc. These lenses have zero PK compatability. Life is too short. If I want to play with those lenses, I'll get a NEX.

[Medium FormatPro]

using his lumix camera and a really old manual focus 400 2.8 Canon lens at an Astronomy show (an equivalent of a 800mm 2.8 lens!) The camera looked like a lens cap on the end of that huge lens

Could have been a T-Mount lens; in which case... Some (but definately NOT all) T-Mounts lens with their removable T-mount adapters can in fact be used on more than one system. But the aperatures are frequently "quite dark" on most t-mount lens.

[Joe Nation]

Check out Leitax for a range of mounting flanges to convert Leica, Zeiss and Olympus OM lenses to Pentax cameras (as well as lots of other non-Pentax combos).