от:iFuzzy
Размер никоновского байонета не позволяет, слишком узкий для АФ контактов на 1.2.
The problem with developing such a fast lens primarily lies in the limitations of the Nikon F mount. Compared to the Canon EF mount, which has a large diameter of 54mm, the Nikon F mount is only 44mm. That’s a big difference in size! If you look at the rear of the Canon 85mm f/1.2L lens, you will see that even the 54mm diameter was not large enough to accommodate such a large aperture – Canon literally had to place the lens contacts right inside the lens mount. Since CPU contacts take additional space, it would be extremely difficult for Nikon to accommodate them, given how large the rear element would have to be.Подробнее
текст взят отсюда
http://photographylife.com/nikon-58mm-f1-4g-announcement
автор - Назим Мансуров, живущий сейчас в Денвере.