Canon's Serenar fast normal — 50mm f/1.9 in Leica Thread Mount, manual focus.
The Canon Serenar 50mm f/1.9 is a fast normal rangefinder lens made in Japan for the 39mm Leica screw thread. It comes from the late-1940s Serenar period of Canon's rangefinder lens line, when the company was building faster standard lenses. It gave Leica-thread and Canon rangefinder bodies a bright, general-purpose fifty.
This is a manual-focus, rangefinder-coupled Leica Thread Mount lens with a 50mm focal length and a maximum aperture of f/1.9. The mount is the 39mm Leica screw thread (LTM / L39 / M39). Focus and aperture 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.
The 50mm normal field is the classic all-round rangefinder view, and the f/1.9 aperture gives useful speed for lower light and gentle subject separation. Fast fifties of this vintage tend to render smoothly wide open with rising sharpness as they are stopped down. It suits street, travel, portraits and everyday shooting.
Buying used, look closely for haze, fungus and balsam separation in the cemented groups, all common in early fast glass. Check the coatings for cleaning marks and wear, inspect the aperture blades for oil, and confirm the focus helicoid is smooth. Test rangefinder-coupling accuracy on a body. It adapts well to Leica M via M39-to-M and to mirrorless using M39-to-E, M39-to-Z or M39-to-RF adapters.