Budget Nikon 20mm ultra-wide in Non-AI mount, affordable quality Nikkor optics convertible for modern body compatibility.
The Nikon Nikkor 20mm f/4 Non-Ai is a vintage ultra-wide prime for the Nikon F mount from the pre-AI era. Non-Ai = lacks the Automatic Indexing (AI) coupling for open-aperture metering. Can be used on modern Nikon bodies in stop-down mode or with AI conversion. Nikon F mount.
f/4 maximum aperture. 20mm focal length (full-frame ultra-wide). Non-Ai coupling (pre-1977). Manual focus. At approximately 280g. Nikon F mount.
The Non-Ai 20mm f/4 is a vintage ultra-wide from Nikon's pre-AI era. Non-Ai lenses can be used on modern Nikon F bodies in stop-down metering mode, or the AI conversion tab can be added by a technician. A rare and optically capable vintage ultra-wide.
On the used market the Nikon Nikkor 20mm f/4 Non-Ai is a vintage specialist ultra-wide. Condition checks: front element, focus ring, aperture blades. Nikon F mount — non-AI (stop-down metering on modern bodies).