Sharpness may change at various distances, but it shouldn’t be a massive difference for a portrait. The bigger factor will be critical focus at f/1.8, I think.

I am Gregory. I recently bought a Nikon D 750 and Nikkor 85mm f 1.8. I want to know from you if I shoot at an aperture 1.8, how far can I be from the subject? To get the same frame, I can shoot at different distances from the subject and crop the images to get the same frame. But not all will look equally sharp. I think there must be a maximum distance when shooting with auto focus mode at wide open apertures for tack sharp image?

Hey Eloise, that’s great! You’re getting a head start shooting concerts and festivals so early. Don’t forget to have fun. I’m very happy the stuff I post here has helped your photography!