D800 focus with 1.4 prime lenses is very variable and inaccurate

That really sucks, I'm sorry you're having problems. I exchanged my first D800, which had soft focus on the left side, for a 2nd D800 which focused better. I've never tried a 1.4 prime lens like you describe, most of my lenses are f2.8. Hopefully this is something a software fix can address. I am a little shocked by the relatively *infrequent* firmware updates from Nikon. This is my first higher-end Nikon DSLR, is it normal to only update the firmware once or twice per year?

Anyway, I hope you find a solution to your problem.

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"I've been in more laps than a napkin" - Mae West