A Puzzle.

I have a fully manual Cosina 200mm prime in excellent condition which I am anxious to use but which will not work when mounted on either of my K5's.
The mount is identical in all respects to other K mount legacy lenses that I own, both Pentax and others.

The cameras simply will not allow the lens to close down to the chosen aperture regardless of mode or any other setting - all exposures are at maximum aperture.

The puzzle is that the lens works perfectly on the K20.....am I missing something here? After all there are no obvious differences between the mounts on the two camera bodies.

The aperture blocks in the two K5 bodies are obviously interfacing with the aperture lever on the lens, as the iris is moved to maximum aperture as the lens is mounted on the camera.

This is the only manual lens, among the 'several' that I have, to behave in this way.

Roger

You do need to set the appropriate custom setting to permit use of the aperture ring. Perhaps this hasn't been done on the cameras causing the problem?

And try setting the program dial to M. You then acquire the correct shutter speed by pressing the green button after having set your desired aperture.