#4. "RE: Check out these pics - do I need to return this?" In response to Reply # 3
the subject was focussed on once with the centre focus point, once with the left focus point and once with the right focus point. These images are crops from the location of the centre focus point (pic 1), left focus point (pic 2) and right focus point (pic 3).
Otherwise the subject would have been far too small or the photos far too big to upload.
I think the crops should be sufficient for a quick illustration of the problem. Other photos I've taken with the same method show exactly the same pattern, including the FoCal software.
#6. "Thanks for your replies - I got a new copy of the D800" In response to Reply # 0
It performs much better on the left AF point.
Autofocus is still very hit-and-miss wide open and at f/2 with my 50mm f/1.4G, but now I can often get very good results on the leftmost AF point - with my previous version of the camera, I could NEVER get a sharp shot with it.
Stopping down the 50mm f/1.4G gives much more reliable AF results on all points tested.