I use Takumar (Asahi Pentax) lenses on my DRebel and now on a 5D mkII. My first adapter looked like the one in your link. It was too thick, my lenses could not focus at infinity. I sanded it down to improve it, it worked but I don't use it anymore since I got an (Ebay) adapter with focus confirmation that has correct infinity focus. With a FF camera you should be careful, some old lenses stick a little deeper in the body than Canon lenses, and block the mirror. With a 30D with a smaller mirror that won't be a problem. Some Takumars are very fine lenses, my 1.4/50mm SMC Takumar is wide open very much better then the copy I had from Canon, my 17mm fisheye Takumar is probably not as good as Canon's but I already had it...
