Does anyone have any experience in modifying non-AI lenses to an AI capability? Some of the more enticing lenses I am after are the pre- AI versions and are at great prices. However, they also seem to not have the AI kits for them available anymore. How hard is it to modify the lens yourself? What tool(s) are required? What are the measurements for the cut-out and what is the reference point to begin the cut and how long? Do you grind it out and if so, what do you do to protect the lens from 'inhaling' the shavings? Any web site with this info? I have examined the archives here and searched the Google with no success. thanks in advance for your help!