[Don Schaeffer]

I bought a Vivitar 28mm f2.5 lens on e-bay. The optics are great. The lens is frozen on wide open so I can control exposure with shutter speed. The lever that closes the lens down is stuck. The diaphragm of the lens works fine though--off the camera. Why can't I use the lens in a stop down mode?

I use it with my D40.

[Toad]

Not quite sure I understand the problem. Is there an aperture ring on the lens? If so, when you spin the ring, does the lens stop down?

Nikon "G" lenses do not have aperture rings, and are stopped down via a thumb wheel on the camera body itself. Non-G lenses cannot be controlled this way, but you still should be able to set aperture manually via the dial on the lens.

As I say, maybe I am not understanding the problem.

[Don Schaeffer]

Yes. The lens' aperture ring works fine off the camera. But when I put the lens on the camera it does not stop down. The lever on the back of the lens is stuck.

[Don Schaeffer]

I'm not going to use this lens any more. Waiting for delivery of a Nikkor 28 mm pre AI.

[Don Schaeffer]

I found that if I mount it wrong--so the diaphragm pin on the camera does not touch the pin on the lens, it works fine. I just have to manually focus and adjust exposure. I use it on manual.