Today I encountered a focusing problem that could be reproduced at will with either the Nikon 105mm f/2 DC or the 180/f2.8D. The D3 thinks the frames below are in focus; the focus confirmation light inside the viewfinder goes on (solid), and the focus confirmation beep is heard. (Both of these lenses are the klunky old style focusing ones, not AF-S; I haven’t observed any problems with AF-S lenses.)
Nikon D3 + 105mm f/2 DC. Autofocus, full frame.
Nikon D3 + 180mm f/2.8 ED-IF. Autofocus, full frame.
Turning the D3 on/off does not fix the problem, and as far as the D3 is concerned the image is in perfect focus—forever. Only by switching to manual focus, then refocusing farther away, then switching to autofocus again does the D3 come out of its stupor. Maybe this is a general problem, or maybe it’s just my particular D3.
I also observed focus accuracy errors with both lenses; forcing refocus repeatedly on a tripod-mounted camera resulted in variable sharpness ranging from spot-on to noticeably blurred. Sorry to burst anyone’s bubble, but neither lens is acceptable for work where reliable sharp focus is required (see also The Sharpest Image). The 180/2.8 is brand-new; the 105/2 DC is a few years old.