Thanks, Armando. I've used the lens on an FX body for the first time and found that the slight vignetting of the lens used wide open gave a nice "spotlight" effect.
Anirban, thanks! D750 inspires me a lot. It was calibrated at the Nikon service along with AF-S 50/1.8G, and not only the AF but also the "green dot" is very reliable now.