I have looked at other areas in the photo that are as far if not farther away from the camera than the tower area "kers" asked me to look at. What I now think is going on is that this individual lens may have a problem in that area as other areas appear to have much crisper detail rendering
Ellis, I think it has to do with the complexity of this zoom lens. For a 24-70 zoom lens that costs 1500€ or so I think it is a good performance.
It was launched in the 12MP Nikon D3 era.
I did not buy this zoom because i (also)saw some strange soft areas right in the middle sometimes in my test-photos- also the 24mm performance is not that good.
If you use the 85mm 1,4G or one of the PCE lenses etc I am sure the image will be better.
36MP askes for better lenses. I can see that Zeiss with their new 15mm lens already starts to make these, but the price point will be above 2000€.
Eventually when also the MFB people start using the d800 there will be a market for these more expensive lenses.