I might have a silly question, might be already asked. I was looking to the resolution test of Tamron AF 17-35mm f/2.8-4 done with D200. MTF is around 2200 in the center and 1900 in the border and it is written that the max (theoretical I believe) is 2320. Then I looked for Nikkor AF-S 20mm f/1.8 G where the max is 4000, measured are around 3900 and 3300. When I normalized the measured values to the max of their own, it seems that MTF of both lenses are the same. I have a D810 with the Tamron and considering the 20mm f/1.8 but if the resolutions will be the same I won't bother for a faster lens. But the price tags and dxo test do not say so. What am I missing?