I have got a couple of old K-mount lenses and most of them work just fine on my K5 (metering via green button or preview..., manual mode etc.). Now I do have two lenses that do not stop down when metering or shooting, i.e. the aperture stays wide open all the time when mounted.
The Lens I care about is a Cosina 135mm f/2.8 (Cosinon-T MC) which appart from this problem does take nice pictures.
What I have done already:
- I checked and compared the aperture (and the trigger) to my other lenses and couldn't detect any differences. The trigger seems to be at the same place, it triggers, the aperture opens and snaps back.
- When I take out the trigger so that the aperture is not coupled to the camera the lens works fine (except of course, that my viewfinder gets darker when closing the aperture...).
- Mounted on an old Pentax ME it works just fine !?
Maybe someone has an idea what the problem could be?
Last edited by FH_le; 01-21-2011 at 08:38 AM.