further to what I wrote yesterday I spent almost the whole morning testing both my D800 and D4 with Reikan FoCal Pro to see how different AF points perform and what is the variance between them.
The most interesting observation is that the average Quality of Focus (QoF) for any of D4 AF points is much higher (about 20%) than for D800, all other factors being the same (same lens, same target, same distance, etc.) Another interesting finding is that the variance for QoF among 51 AF points in D4 is significantly lower (about 20% again) than in D800.
It seems that the AF points, which can almost always be relied on are the 9 central ones. The other AF points show much higher discrepancies, depending on the lens, distance from the target and lighting.
In general it seems that the variance between 100% QoF for the best AF point and about 50% for the worst one is pretty common, regardless of the testing setup, which really surprised me, because I expected much more accuracy and consistency.
Anybody performed the same tests with Reikan FoCal Pro? I would like to hear about your results.