My new D800 has Left/Right AF issues too :(

My experience is that there is no way to measure the optimal AF Fine Tine with a precision more than 3 AF Fine Tune units. And such a precision can only be obtained with a slanted ruler like the LensAlign tool or what is described in the Nikon link I gave above. This limit comes mainly from the fact that even in bright light, with a target with high contrast the AF system never focuses exactly at the same position, and this variation is roughly 3 AF Fine tune units.

If you get a difference of 3 AF fine tune units in between the AF sensors, you are within th noise of your measurement which is what I would define as a "perfect" body. Wether your camera is a D800, a D700, a D600, a D4, a D3, a D3X you will always measure some difference in between the optimal AF Fine Tune of the different AF sensors.

The question of what is acceptable has no offical answer from Nikon. Falk lumo is the only person I've seen addressing the issue correctly, and after measuring different bodies (not only D800, not only Nikon) his findings are that you should aim for a difference:
- below 20 for a f1.4 lens
- below 10 for a f2.8 lens

I had a difference of 12 AF Fine Tune units between the left and right AF sensors with a D800 and a 85mm f1.8 lens. If you choose a number in the middle, there in almost no way to make out the difference on a flat target with AF phase detect and AF contrast detect.

I'll be happy to learn more, but so far this article from Falk Lumo ( http://www.falklumo.com/lumolabs/articles/D800Focus/SensorArray.html ) is the only on I know to address the issue quantitatively. And my experience gives the same numbers.