Originally posted by Docrwm Thanks for all the help. I thought I saw someone say that you can mount an adapter to a M42 mount lens semi-permanently and then it will work like a K mount. Is that not possible or a bad idea?
With the non-flanged variety of the adapter one could 1) remove the lock spring and 2) then attach the adapter to the lens with some mild adhesive. Removing the lock spring is essential: otherwise the ring will lock on the body as usual, but you can't access it to unlock it from the body, so you have a stuck lens. Without the lock spring the lens won't lock on the body, though, and this could be an accident waiting to happen.
The adapter without the flange has a lock spring because M42 lenses do not have the k-mount locking pin cavity. The point of the flange is having the locking cavity in the flange, but having the flange ruins infinity focus.
(An M42 lens with a semi-permanently attached k-mount adapter still doesn't have the k-mount aperture lever and won't work like a k-mount lens in that department, of course.)