http://www.nikonchat.com/nikon-d7000-aperture/

Unable to lock the ring tightness in nikon d7000?
hello every1, I'm using a lens with an aperture ring and closing the opening is only ISI f 22, but when I want to switch to another number I can not block? donno what is the problem!
The problem is not read or understand the manual of your camera. Once you have a lens with an aperture ring to close in F22 (or F32, F16, which is the highest) and the body uses to set the aperture as you would with a lens without an aperture ring. To my knowledge, it would take a d300 or better to have the option of using the aperture ring on the lens
Nikon D7000 Unboxing