I've been scouring the internet trying to get feedback from unbiased D800 users on how well the AF works apart from the left focus disaster, and I've noticed a number of references ( talking about DSLRs in general ) to using manual focus as if this would eliminate any AF inaccuracy.
I cannot really see how this would improve the situation on any camera.
1. The screen doesn't lend itself to MF surely? My film cameras with MF had a split prism section in the middle surrounded by a fresnel ring and then the rest was ground glass. Easy - peasy! I've yet to see a DSLR focus screen anywhere like as useful for this. Are people really managing it? I doubt I'd be more accurate than the AF using my D700s
2. You could then rely on the AF point lighting up when you achieve focus by moving the ring, but then surely you're back to the same situation as using the AF system as regards accuracy? The point would light up at the same setting that the camera would choose for AF.
3. Live view maybe is the only way I can imagine it but it really isn't practical in most portrait situations either in or out of the studio