Focus issue in D810 after repair

Question

Just got my D810 back from Nikon repair for a USB port problem. The camera was reset completely, including all my settings, date, etc. It has the latest firmware.

After doing my usual setup, I used my spyder lenscal to tune the focus. The adjustment on my Nikkor 24-70 2.8 needed a +4 before the repair and now, +18. Same on 5 other lenses including 3 sigma art primes and a Nikkor 70-200 2.8. I know the body quite well, but just wondering if there is something obvious I am missing here. My D750 body needed some adjustment on a few lenses, but not in the same ballpark.

Answer 1

If they replaced side ports subassembly board, it's possible that the camera body was completely opened up. If that's the case, then the lens flange was probably removed, and perhaps even the mainboard, including imaging sensor, was moved, removed, or otherwise shifted position. After reassembly, it is virtually guaranteed that the registration distance (the distance from the front face of the flange to the sensor plane) changed by a minute amount. The change is entirely within tolerances, but is one of the reasons cameras have microfocus adjustment, to allow for reasonable tolerances in variations among lenses and flange—sensor precision.