I have four lenses, (2 AF Nikons, 1 Tokina AI and 1 Vitacon AF). Of the AF lenses:
  • my F4s recognises the two Nikon AF lenses, and the AF works correctly. The Vitacon lens is recognised as a 'CPU' lens, but the AF does not work.
  • my F90x recognises the Vitacon AF lens, and the AF works correctly. However, neither of the Nikon lenses are consistently recognised as CPU lenses at all (the 50/1.8 is sometimes recognised, but more often - not). i.e. the camera deals with both as if they are simple AI lenses.

It's looking to me like there's something amiss with the F90x - possibly a dodgy CPU connection in the body - although the fact that one lens works is a puzzle to me.

Has anyone any experience of investigating such electronic repairs? It looks to me like the contact block is screw-mounted behind the lens mount. So it may be as simple as removing the lens mount, removing the block and taking a look.

Or perhaps not... I hate the sight of a small spring leaping for freedom