Nikon's rangefinder telephoto — the four-element Nikkor-Q 13.5cm f/4 in Leica screw mount.
The Nikkor-Q 13.5cm f/4 is a telephoto rangefinder lens from Nippon Kogaku (Nikon) in the Leica screw mount, dating from the late 1940s. Nikon engraved focal lengths in centimetres, so 13.5cm equals 135mm. It was Nikon's early 135mm for the rangefinder system, sitting at the long end of the line where an accessory finder or reflex housing helped with framing.
This is a manual-focus, rangefinder-coupled Leica Thread Mount lens with a 135mm focal length and a maximum aperture of f/4. The -Q suffix stands for Quattuor, Latin for four, meaning a four-element design. That four-element construction is the product distinction the letter records. Filter thread and weight should be confirmed on the specific example rather than assumed.
At 135mm the lens reaches well beyond a standard for distant subjects, tighter portraits and detail work. The f/4 aperture keeps it relatively compact for a telephoto while still separating the subject from the background. Framing a 135mm on a rangefinder typically calls for an accessory finder, and the longer focal length rewards careful focus for sharp results.
This early 135mm Nikkor is collected as part of the rangefinder system and appears on the used market fairly regularly. Inspect the elements for haze, fungus, separation and cleaning marks, and check coatings for scratches. Confirm the aperture blades are dry and the focus turns smoothly across its longer range. The screw mount adapts to Leica M via an LTM-to-M ring and to mirrorless with a further adapter, which eases framing at this focal length.