I'm not sure if this helps, but I would leave it alone and shoot it on a camera that does not require the modification, like a plain prism F2. On which camera are you planning on using it? Do you have a hand held meter? My 50 1.4 non-ai is a dreamboat and I use it on my very old F2 - works insanely well and is such a nice lens. Sorry, blah blah blah.