Nikon's early ultra-fast normal — the manual-focus Nikkor-S Auto 55mm f/1.2 for the F mount.
The Nikkor-S Auto 55mm f/1.2 is a very fast standard prime for the Nikon F system, introduced in the mid-1960s. The S code marks its element count, and it was one of Nikon's earliest ultra-fast normals, giving F-system photographers a bright aperture for low light and shallow depth of field before the later 50mm f/1.2 designs.
This is a manual-focus Nikon F lens with a maximum aperture of f/1.2 and a fixed 55mm focal length, using an automatic diaphragm for full-aperture viewing. It is a fast double-Gauss standard operating with normal reflex viewing. Only the verified focal, aperture and mount are stated; construction details are omitted to avoid error.
Wide open at f/1.2 the lens gives a soft, glowing rendering with shallow depth of field and rounded highlights, sharpening markedly as it is stopped down. This look suits portraits and atmospheric low-light work where the bright aperture and gentle rendering are both wanted. It is a character lens as much as a technical one.
On the used market this early 55mm f/1.2 is collectible and commands higher prices as a fast vintage normal. Inspect the large front and rear elements for haze, fungus and separation, check coatings for scratches, confirm the automatic diaphragm operates, and test focus damping. It adapts well to mirrorless where the wide-open glow is prized.