Nikon built the Z mount with an unusually large diameter and a short flange distance that the company has been quite candid about: it was designed, in part, to make the Nikkor Z 58mm f/0.95 S Noct possible. A lens so demanding optically that no existing mount could accommodate it. A lens that costs more than many used cars. A lens that, held in the hand, feels less like a photographic tool and more like a proof of concept — Nikon demonstrating what it could do if relieved of all practical constraints.