Nikon's early rectilinear super-wide — the manual-focus Nikkor-QD Auto 15mm f/5.6 for the F mount.
The Nikkor-QD Auto 15mm f/5.6 is an early rectilinear ultra-wide for the Nikon F system, introduced around 1970. The QD designation follows Nikon's optical-code convention, and it sits among the first practical super-wide non-fisheye Nikkors, aimed at architecture and landscape where straight-line rendering was needed at a very wide angle.
This is a manual-focus Nikon F lens with a maximum aperture of f/5.6 and a fixed 15mm focal length, with an automatic diaphragm for open-aperture viewing. It is a rectilinear design that keeps straight lines straight and uses built-in rear filters rather than a front thread because of its bulbous front element. Only verified figures are given; element counts and weight are omitted.
The rendering emphasises geometric correction across a very wide field, holding architectural lines straight where a fisheye would curve them. Its slow f/5.6 aperture suits deliberate tripod work in architecture and expansive landscape rather than handheld low-light shooting. Depth of field at this focal length is extensive, easing focus.
On the used market these early QD super-wides are scarce and sought by collectors of vintage Nikkor glass, with prices reflecting their rarity. Inspect the large front element for scratches and coating haze, confirm the built-in filter mechanism turns freely, and verify the automatic diaphragm closes correctly. It can be adapted to mirrorless, though its deep rear group warrants a compatibility check.