Need to modify an M-42 mount Adaptall lens for use on a Pentax K-mount camera
without unscrewing delicate parts?
PROBLEM: My Adaptall lens, M-42 mount, would not stop down on my K-50—the small pin that closes the lens’s diaphragm does not get depressed by a digital camera.
SOLUTION: Using an X-Acto knife, I cut off the tip of an empty ballpoint pen refill (about 1/8 of an inch), slit it down one side to make a collar, and gently wedged that into the Adaptall ring—thus permanently lifting the little platform that the pin would push up.
Now, when I turn the aperture ring, the lens stops down, and the camera meters correctly (on the K-50, this works in AV mode).
Last edited by fotograffiti; 01-27-2016 at 10:47 AM.
Reason: typo