As I mentioned in my first MF lens post, Bob has a great article on manual focus lenses for the Canon EOS. He writes it turns out that the diaphragm coupling lever which sticks out from the back of the lens makes [adapting Pentax K lenses on a Canon EOS body] impossible. This is the standard answer you will get, and at the moment I cannot find any adapters on eBay or any other retailer. Lucky for us Michael Pollet has put this claim to shame. In his article he writes a detailed instruction of how to adapt a M42->EOS adapter to the Pentax K lenses instead. I was planning on doing something similar but haven’t received my Pentax K lenses yet so I haven’t been able to tell if its feasable. Luckily he’s shown that if at loss, this is a great way to go. He reaches infintity focussing and has done some quite interesting modification. If you’d like to mass-produce such an adapter he even offers to send you a prototype for inspection. Hopefully it won’t be too long until we can see such product on eBay. Until then we’ll all get our old metal working equipment out.