Thanks for raising this topic. I've had the Nikon 12-24 f.4 DX for 10 years and got good use from it with D200 and D7100. I've not used it since getting into FX. If I understand correctly, on my D850 dialed in DX format, I've got a 18-35 with 20 MP, and using full FX I get a functional 18-24 with 45.7 MP ? Is this right? I just might start using it again while I wait for the 14-24 f.2.8 replacement.