I recently modified my 40mm Summicron-C to bring up the 35mm framelines on my M6(i.e. I took a file to it). There are a few posts on p.net about this, but I never found any photos of the final result. So here are a few shots of mine. For details of how to do the modification go to this previous post: http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00AQS2 N.B. Watch out for filings, I suspect they could get into places you don't want them! I stuffed lint free rags into anywhere I wanted to protect. You might want to slip a piece of card under the 'flange' to protect the metalwork from scratches. I've found the 35mm framelines to be much closer to the actual 40mm than the 50mm framelines - which are brought up prior to modification. A lot of people on p.net will advise against this mod, however, this really is a simple process - nowhere as confusing as I've made it seem! (This process may devalue your lens, so consider it carefully).