You can use a Pentax lens to EOS body adapter from vendor like Fotodiox. However you will have to cut off the aperture lever and protector from the lens to make it work on the 5D. That is a waste of a good lens since the surgery is non reversible.
I'd say it's far from a waste, unless you're shooting Pentax film bodies. Pentax digital bodies are lagging quite far behind their stellar lenses. I think modifying this lens to use it on full frame Canon is doing it justice.
If Pentax/Samsung pull their thumb out and decide to make a FF digital (not likely) then it's a different story.
If you have a chance, try it on a 1.6x crop body first, as this doesn't require the aperture leverectomy. This way, you can see if you like it (as far as you can tell on the CF body), and then decide if you want to keep it. I agree with thrice's comments, and add that it will still work on Pentax bodies, but only with manual stop-down aperture control.
trifilmer wrote:
Has anyone done this to their lens? (the leveroctomy)
When I went from K10D to 5D I contemplated this. In the end I sold the FA31 as I figured I could live without the CA and the strange mechanical build of the FA31. Better get some money for it. I bought a nice Zuiko 24/2.8 instead.
I did remove the aperture lever and its protecting shield from my FA20-35. It works a bit so-so at its widest end but is one of the few wide angle lenses with decent bokeh (when not everything is in focus that is... It was a 3 minute work using a plier including covering the rear element and finding the plier.
