I'm just curious about how this is supposed to work, so I can pass this on to the owner of this set up. We met up yesterday and he had his D90 and this lens so we could have a play with it. I looked at the lens and saw the list of f stops there, and it was set to f22. Worked fine. I asked him about putting it to other f stops and he said the guy that sold it to him told him he's best to leave it on f22 otherwise auto focus won't work and manual focus is hard with this lens. Well I can't help but fiddle with knobs and buttons so I tried to set it to another f stop - but the camera doesn't like it, comes up with an EE error. I set the camera to manual focus, manual everything, and still, EE. There wasn't anything I could find that could get rid of the EE error, other than locking the lens at f22.

I've read a couple of posts elsewhere that say that it must be on f22 and that you then set the f stop in the camera body. I don't have the camera here now to try anything, so I don't really understand this. If the lens is set and locked at f22, can the camera then choose f1.8 for instance? Is it possible to take a photo at f1.8?

The lens is put on f22, then the f-stop is controlled from a control wheel on the camera. Yes, it can be at 1.8. All that is adjusted with the control wheel, not the aperture ring. This is true of most all AE Nikon cameras, even film cameras.

There are usually two wheels. One on the front (under your index finger) That is usually the Shutter speed control. And one in the back (under your thumb) that is typically the aperture control.

So. To re-iterate. The lens ring is set at f22. But the ACTUAL aperture of the lens, is controlled by the camera body, not that control ring, on AE/AF Nikon cameras.

The ring would still be used on manual focus camera bodies.

thanks rogue, great explanation.