The 28-70/2.8 has long been recognised as among the best ever made by Nikon. I'm happy to report that the new 24-70 takes this quality even further. It has a very modest amount of field curvature at 24mm and virtually none at 70 mm, so you can apporach your subject without fear of the corners going unsharp. Light fall-off can probably be measured in a research lab but is undetectable within the frame of a DX camera, more or less the same behaviour is seen on the D3 but this statement is only tentative until I get my D3 later.
Very sharp images result on-axis at 24 mm even at f/2.8 and the contrast was good all over the frame with corners ever so slightly softer. At f/4 the entire frame at 24 mm appears sharp and crisply defined with excellent contrast and colour saturation. Stopping down further changed little of these traits until you got near f/16, where lowering of contrast and the onset of loss of detail commenced to be more visible. Still, I would not hesitate shooting at f/16 even on the wide end of the range.
For the long end, f/2.8 delivered sharp images across the entire frame and this improved further at f/4. Absolutely state of the art optical performance and the enhanced acuity and better micro-contrast compared to the identical capture with the 28-70 were plainly visible. Image quality held up well to beyond f/16, even f/22 looked very acceptable, a most unusual finding. <snip>
I'll run tests on this lens on a D3 later to confirm these findings, but as of now, the new 24-70/2.8 Nikkor is the reference for all other midrange zoom lenses.