Hi one and all,

A mate has the following gear - Nikon D90 and the Sigma 50-500 lens. The issue he is having is primarily with this lens combination, and it is also intermittent in its nature which is why he's more puzzled as well!

When he's using the gear, generally aviation so no chance of resetting composition and also fast moving subject, looking through the viewfinder the f-stop setting goes to f--! After 'taking' the shot, and looking at it through the screen, it is a black image. He shoots at f.9, camera is set to full manual and shooting RAW. He also mentioned that from memory, it also occurs when at a focal length above 300mm...

Camera is out of warranty, but when he called Lidcombe, they mentioned a lag time of 5-7 working days to look at it, let alone fix a problem that may be with the body. The lens is not even a year old, still under warranty, and when I went back to where we got them (I got same lens only Canon mount), I was given details of where it could be serviced under warranty over at Mascot (which suits him as he works at the airport).

Has anyone else had this sort of problem, and if so, was it a lens or body issue, and what were the corrective measures taken to fix it.

Thanks in advance for any assistance!