Nikon's faster rangefinder 35mm — the W-Nikkor 3.5cm f/2.5 in Leica screw mount.
The W-Nikkor 3.5cm f/2.5 is a wide-angle rangefinder lens from Nippon Kogaku (Nikon) in the Leica screw mount, introduced in the early 1950s as a faster companion to the earlier f/3.5 version. Nikon engraved focal lengths in centimetres, so the 3.5cm marking equals 35mm. It became one of the more common Nikon rangefinder wides and a practical everyday choice for thread-mount users.
This is a manual-focus, rangefinder-coupled Leica Thread Mount lens with a 35mm focal length and a maximum aperture of f/2.5, brighter than the f/3.5 model it followed. The W prefix denotes a wide-angle Nikkor. The centimetre engraving reflects Nippon Kogaku practice. Any further construction detail should be verified per version rather than assumed for the sake of accuracy.
The 35mm focal length is the workhorse width for street and documentary photography, giving a natural yet inclusive perspective. The extra speed of f/2.5 over the older f/3.5 makes it more usable in shade and indoors. On period rangefinder bodies an accessory 35mm finder was often fitted. Its handy size keeps a rangefinder outfit compact for daily carry and travel.
This faster 3.5cm Nikkor is popular with both users and collectors and appears on the used market with some regularity. Check the glass for haze, fungus, separation and cleaning marks, and inspect the coatings for scratches. Confirm the aperture blades are free of oil and that the focus helicoid is smooth. With an LTM-to-Leica-M ring, and a further adapter, it mounts on Leica M and mirrorless cameras alike.