Nikon's fast Sonnar-type standard — the seven-element Nikkor-S 5cm f/1.5 in Leica screw mount.
The Nikkor-S 5cm f/1.5 is a fast standard rangefinder lens from Nippon Kogaku (Nikon) in the Leica screw mount, introduced in the late 1940s. Nikon engraved focal lengths in centimetres, so 5cm equals 50mm. Derived from the Sonnar design tradition, it was the fast 5cm in Nikon's early rangefinder line before being superseded by the f/1.4 version.
This is a manual-focus, rangefinder-coupled Leica Thread Mount lens with a 50mm focal length and a maximum aperture of f/1.5. The -S suffix stands for Septem, from the Latin for seven, meaning a seven-element design. That seven-element construction is the product distinction recorded by the letter, consistent with the Sonnar-derived layout. Further details should be verified per version.
As a Sonnar-derived fast standard the 5cm f/1.5 has a reputation for smooth rendering, with a gentle transition to out-of-focus areas that suits portraits and low-light work. Wide open it prioritises a soft, flattering look over clinical edge sharpness, gaining crispness as it is stopped down. The 50mm perspective keeps it versatile for street and general use.
This fast Sonnar-type Nikkor is collected for its rendering and its place in Nikon's rangefinder history, and good examples are sought after. Check the elements for haze, fungus, separation and cleaning marks, since Sonnar-type glass can show internal haze with age, and inspect coatings for scratches. Confirm the aperture blades are oil-free and the focus is smooth. An LTM-to-Leica-M ring, plus a further adapter, allows use on Leica M and mirrorless cameras.