Yashica's fast fifty for M39 — the Yashinon 50mm f/1.8 screw-mount standard prime.
The Yashica Yashinon 50mm f/1.8 in M39 Leica Thread Mount is a fast standard prime from Yashica, adapted for the Leica Thread Mount compatible rangefinder cameras. Yashica produced M39 lenses for their own Electro 35 and related rangefinder cameras, which used the LTM standard.
The lens delivers 50mm at f/1.8 maximum aperture with M39 screw thread coupling, manual focus and aperture, and full-frame 35mm coverage. Yashinon optical quality in the standard prime range is generally well-regarded for the era.
The Yashinon 50mm f/1.8 in M39 mount provides fast standard prime coverage for Yashica's own rangefinder cameras and, via M39-to-M adapters, for Leica M bodies and Sony E-mount with appropriate adapters. Yashica's glass has a growing collector following.
Check M39 thread for clean coupling. Test aperture blade operation at f/1.8. Inspect element condition and Yashinon coating. For M body or modern mirrorless use, verify M39 adapter availability and test rangefinder coupling accuracy if applicable.