In the Nikon lens line-up, the two Nikkor lenses compared here offer very similar specifications with the exception of the maximum aperture. Comparing them side-by-side shows where the extra expense is justified in going for the Nikkor 28mm f/1.8G. Looking at the overall DxOMark scores on the D3x, the Nikkor 28mm f/1.8G is at the top with 29 while the Nikkor 28mm f/2.8D only manages 23. The Zeiss lens fits in the middle, scoring 25.
In terms of sharpness the 28mm f/1.8G manage 19P-Mpix and is at the top end of the table for wide-angle primes. The 28mm f/2.8D, with a score of 14P-Mpix is down at the lower range of the table (-however given the lower price point and simpler optical construction this is to be expected). The Zeiss with 16P-Mpix fits in the middle.
The distortion scores between the three lenses are very similar - sufficiently so that there would be no obvious difference in final image prints. In the lens shading, or vignetting, results however, there is an interesting switch between the Nikkor 28mm f/2.8D and the Zeiss, with the lower priced Nikkor scoring -1.8EV to the Zeiss’ -2EV. Both though are beaten by the Nikkor AF-S 28mm f/1.8G scoring -1.7EV and hence offering the most even light transmission across the image frame.
Looking at the Chromatic Aberration scores, again the familiar order is restored, with the 28mm f/1.8G scoring 10µm to the Zeiss’ 12µm and the 28mm f/2.8D’s 17µm. With these scores, all three will show some level of Chromatic Aberration, but it will be least intrusive on the Nikkor 28mm f/1.8G images. For CA measurements, a score of 5 is determined to be noticeable and corresponds to around 1pixel of CA around high contrast edges on most cameras, so with the 28mm f/1.8G you can expect up to 2pixels of CA around high contrast edges.
Overall, the Nikkor 28mm f/1.8G provides the best results of these three in all lens performance tests.