Originally posted by froeschle Have you really tried this? Communication between adapter and body is required for AF functionality (digital-info contact). Furthermore, one has to take care not to intervene with the auto-focus transmission shaft. So the other solution is not only more convenient but also less error-prone.
If you look at the diagrams in the links that you've provided, you can see where the contacts are on the body and on the lens. You don't need to cover all of the lens mount surface with foil, just where the body contacts will be when the lens is mounted. I have taken a non-infinity black aluminum m42 adapter, foil taped the contact portion of the mount and when used in conjunction with the AFA 1.7x adapter, AF works very well.
Place the adapter with the red dot at 12 o'clock position, the area that need to be covered by foil is between 4 and 6 o'clock position. Using a small piece of aluminum foil duct tape, trace and cut out the curves of the m42 adapter and carefully paste the duct tape in place. Burnish the tape with the edge of a plastic card to make sure the bond is strong and the the tape is as flat as possible. Screw the adapter on to an m42 lens and it's ready to go.
Thanks,