It will be M42 mount not M52 (doesnt exist as far as I know) Just look up "Genuine Pentax M42 to K adapter" Any good online camera store or any Pentax online store should have it ~$30.
Question to others:
What does it mean if one of these lenses is "Pre-Set"?
Is it really necessary on an M42 mount lens (not Exacta) to do any modifications to get the lens to work with an adapter on our dslrs? Is there a pin or something that must be removed?
Otherwise I assume M42 lenses would work like Pentax M lenses, wide open in AV mode or fully manual in M. Correct?
EDIT: Found this in another thread from riorico:
A note on M42's -- Three sorts exist:
1) No aperture automation -- one aperture ring, or two rings (preset). These are simple to use: Set the aperture and shoot. With a two-ring preset lens: Set the desired aperture, spin the loose ring up to compose, then spin it down to shoot.
2) Aperture automation with a M/A (manual/auto) switch. Set the switch to M and they function just like type (1). Set the switch to A, and you get aperture automation ON FILM BODIES THAT SUPPORT IT, but on dSLRs they stay wide open.
3) Auto-only, no M/A switch. On dSLRs they stay wide open, unless the pin is jammed or glued down, which can reduce the value of the lens. Avoid auto-only M42's unless you're a film-shooter, collector, or lens doctor -- or you like shooting wide open.
Last edited by Deimos; 03-03-2011 at 07:32 AM.