Why can't my Nikon D700 control the aperture of my 24-70 f2.8?

I bought a 24-70 f2.8 from ebay. I put it on the D700 and I couldn't see through the view finder or focus because it was to dark. It appeared that the aperture was closed down and the camera was unable to open it up. I took the lens off and fiddled and put it back on again and it started to work.

Yesturday I did a shoot with large external strobes. The camera was set to the correct exposure which was iso 200, ss200, f8 but the image was over exposed. I changed all the settings on the camera going up to f22 and even going into 'P' mode but the exposure of the final image remained in altered.

Anyone know what is going on. Presumably there's a connection problem or the aperture is physically sticking?

Either the lens is broke or it is an old manual only.

Which exact version of a 24-70mm lens is it? The new AF-S one? Or an older one?

Either way, the D700 should be able to control the aperture of nearly all of them except for the truly ancient ones.

You can't rule out a damaged lens if you bought it on eBay. The fact that the aperture was stopped down when you got the lens may be a hint. Perhaps a return spring is broken, missing, etc.

Take the lens off the camera and compare it with one of your other lenses. There should be an internal lever (you might need a toothpick to get to it), and it should vary the aperture. Compare both lenses and see if they work the same, and they are both easy to move - no binding, etc.

I think then you will get a good idea of the lens condition.

I would guess at sticky aperture blades.

Sorry but it sounds like you bought a duff lens… Aperture blades sticking, probably why the bloke sold it. Get back to him

Well if you really are that stupid buying anything on E=BAY is like playing russian roulette with your money.
probably been dropped in water at some stage.