The Helios 44-2 58mm f/2 is a Soviet-era lens manufactured at the KMZ optical plant in Krasnogorsk, produced in quantities so large that the secondary market is essentially inexhaustible. Clean copies sell for $30 to $80 depending on coating variant and condition. Via an M42-to-Fujifilm X adapter (approximately $15), it attaches to the X-S20 and produces images that Instagram’s lens simulation filters have been attempting to replicate, with limited success, for a decade.

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.