[Stratario]

I bought a Pentax-M 50mm lens about 3 years ago and from what I can remember it worked just fine. Now when I have the lens in my hand and I turn the aperture ring, I can see the aperture opening and closing just fine. But when I put the lens on the body, the aperture opens up at the widest limit and I can't stop it down by turning the aperture ring. I don't know what I'm doing wrong. Can you help please? I want to give it to a friend as a gift. i encouraged him to buy a K10D. Thanks.

[SOldBear]

Now when I have the lens in my hand and I turn the aperture ring, I can see the aperture opening and closing just fine. But when I put the lens on the body, the aperture opens up at the widest limit and I can't stop it down by turning the aperture ring.

That's normal behavior. The lens remains wide open so you can focus easier. It will close down just before and during the exposure.

Now, set the camera mode to M and the aperture ring of the lens to f/16. Face the camera and look at the lens. Hit the green button or turn on DOF review (I assume you leave it the the default setting of DOF review), you should see the lens closing down.

For more info, read this thread.

[Stratario]

Thanks. It works as you described.