Hi,
I just upgraded to a Nikon D750 and put my old Nikkor 50mm D F1.4 lens on it. This lens (and my 50mm sigma macro) works great on my D300 and D7000, but on the D750 it reports the dreaded FEE error.
I solved this problem by changing the Aperture setting from Sub-Command dial to "Aperture Ring", which I don't mind, since I've been using aperture ring settings on my old F3 for 25 years and am used to it.
However, when I do this, the camera does not report the correct aperture on the LCD screen. At F1.4 it reports the aperture correctly. However as I click to smaller and smaller apertures, it gets "off". At F5.6 on the ring it reports F4 on the LCD. At F16 on the ring it reports F8.
The exposures are darker than expected, indicating that the camera really thinks that the exposure is set to the one reported on the LCD screen.
Any ideas?