Nikon's early rangefinder standard — the four-element Nikkor-Q 5cm f/3.5 in Leica screw mount.
The Nikkor-Q 5cm f/3.5 is one of the earliest standard lenses Nippon Kogaku (Nikon) produced in the Leica screw mount, dating from the immediate post-war period. Nikon engraved focal lengths in centimetres, so 5cm equals 50mm. As an early Nikon standard it sits at the modest-aperture end of the 5cm family, below the faster f/2, f/1.5 and f/1.4 Nikkors that followed.
This is a manual-focus, rangefinder-coupled Leica Thread Mount lens with a 50mm focal length and a maximum aperture of f/3.5. The -Q suffix stands for Quattuor, Latin for four, meaning the optic uses a four-element design. That four-element construction is the direct product distinction the letter records. Further details such as filter thread should be confirmed per version rather than assumed.
As a standard 50mm the lens gives a natural perspective for everyday, street and travel photography. Its four-element layout and f/3.5 speed favour daylight and stopped-down sharpness over low-light use. Slower standards like this often collapse into the body for compact carry, though that should be checked on the specific example. It is a straightforward, general-purpose optic for the rangefinder.
These early post-war Nikkor standards interest collectors tracing Nikon's rangefinder beginnings and turn up periodically on the used market. Inspect the glass for haze, fungus, separation and cleaning marks, and check the coatings for scratches. Ensure the aperture blades are dry and the focus turns smoothly and evenly. The screw mount adapts to Leica M via an LTM-to-M ring and to mirrorless bodies with a further adapter.