Quote Originally Posted by Rol_Lei Nut View Post
When you change the aperture on the lens, a cam/lever at the back of the lens moves a corresponding lever in the camera, "telling" it which aperture is set.
Check that:
The cam on the lens is moving when you change aperture & isn't bent
The cam in the camera body can move freely & isn't bent.
If it looks like the two could engage when the lens is mounted.

With the lens off, try moving the camera's cam and see if the meter readings change.

Those checks *might* give you an idea of what the problem is.
Thanks thats exactly it, the cam in the body moves and the meter changes as you'd expect but it looks like something has snapped off and its not quite catching enough with the lens cam. You can almost feel it gripping for a second then slipping off.

Oh well, probably won't bother fixing it! I've got an old external lightmeter that seems to be still fairly accurate so I think I'll stick with that till I can afford something a bit nicer!

Thanks for help everyone.