D800/D800E AF - try to figure this out/what does this mean?

Started May 4, 2012 | Discussions thread
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inasir1971
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D800/D800E AF - try to figure this out/what does this mean?
May 4, 2012

I have a D800 and 5 lenses with a 2x TC-EIII. I fine-tuned them and they are checked at all distances and apertures. The TC is only used with the 70-200. Everything was new. The lenses and adjustment values are:

  • 50 1.8G : -4

  • 85 1.8G : -8

  • 14-24 2.8: -7

  • 16-35 f4 VR: 0

  • 70-200 2.8 VR II: 0

  • 2.0xTC-EIII+70-200 2.8 VRII: -13

Now, I walked into my local dealer because they just received shipment of the grip. Long story but ended up leaving with the grip and a D800E (it was now, or in six months, maybe). Right time right place I guess... Btw, since they had two units - I made sure that the one I was taking didn't have any AF issues.

Anyway, got home and tried out my lenses.

First, the 85 1.8G. Seeing as every single value I've used or seen anyone reporting on the web being negative, I figured out I'd try my luck and use the value I used on the D800 instead of pulling out my LensAlign. And it worked. One step either way and the image deteriorated - with the D800E lens alignment becomes almost trivial as there is no ambiguity since there is no AA filter to blur pixels. In the case of a black/white target - the color of the fringe indicates fornt / back focus (forget which is which now...)

The same applied for all of my lenses + TC combo - all needed identical settings.

Now, contrary to what a lot of people are saying (at least with the center AF point) PDAF on the D800 is as accurate or more so than CDAF.

I find it hard to believe that both units are misaligned by the exactly same amount. I also find it hard to believe that every single lens that requires adjustment is coming out of Nikon plants back-focusing.

What does this mean? I don't know, but I think there is something about the AF system in the D800 / D800E (/ D4?) which causes them to behave slightly differently to other bodies.

I also think that since, with the 1.8G primes there was only one pretty unambiguous setting where they were in focus, the adjustment steps may not be small enough to achieve optimum focus with faster primes. (maybe you need a setting of -8.5)

Any thoughts / ideas?

Nikon D4 Nikon D800 Nikon D800E
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