I am having issues with autofocus with my D700 body and the Sigma 100-300mm F4 lens. Whatever I try, it will not autofocus to save my life. My two other Nikkor lenses autofocus just fine.

I can manually focus the Sigma and control f-stop, etc. and the D700 seems to be reading the information from it. It was working flawlessly with my D300 (which has since been sold), but it's been a while since I used it. I've been searching a few forums to see if anyone else has had the problem, but so far have come up dry.

Thanks!!

I would call Sigma and see if their technical support had heard of any issues with that combination. I have used that lens on a D300 and that combo worked fine, but did not own a D700 when I had the Sigma 100-300 f4. Sometimes an older lens will need to go back to Sigma to work correctly with a new body. Sigmas by design emulate that they are a Nikon lens; in fact every Sigma emulates the same Nikon lens, which is why you can only save one Sigma lens in the AF fine tune.