Canon's wide rangefinder screw-mount prime — 28mm f/2.8 in Leica Thread Mount, manual focus.
The Canon 28mm f/2.8 is a wide-angle rangefinder lens built in Japan for the 39mm Leica screw thread. It belongs to Canon's rangefinder lens line, which supplied screw-mount optics for Canon's own bodies and for Leica-thread cameras through the 1950s and into the 1960s. The 28mm focal length was a popular reportage wide of the era and usually paired with an accessory finder for framing.
This is a manual-focus, rangefinder-coupled Leica Thread Mount lens with a 28mm focal length and a maximum aperture of f/2.8. The mount is the 39mm Leica screw thread (LTM / L39 / M39). Aperture and focus are set on the barrel by hand. Element count, weight and filter thread are omitted here because they are not verified from the gap data.
At 28mm this lens gives a moderate wide angle that works for street, environmental portraits, travel and interiors without the strong perspective stretch of shorter lenses. The f/2.8 maximum aperture allows work in dimmer light than the slower wides in the line. Corner performance and even illumination improve on stopping down a stop or two.
When buying used, check the elements for haze and fungus and the cemented groups for separation (balsam). Look over the coatings for cleaning marks and wear, test the aperture blades for oil, and confirm the focus helicoid is smooth. Have the rangefinder coupling checked for accuracy. The lens adapts cleanly to Leica M with an M39-to-M adapter and to mirrorless via M39-to-E, M39-to-Z or M39-to-RF adapters.