The Yashica 50mm f/1.9 Yashinon-DS (and the essentially identical DSB version) is a well-regarded manual focus vintage prime lens known for its sharpness and smooth bokeh. It was produced with either an M42 screw mount or a Contax/Yashica (C/Y) bayonet mount.
Key Features and Specifications:
Mount Type: Available in M42 screw mount (referred to as Yashinon-DS) and Contax/Yashica (C/Y) mount (referred to as DSB).
Focal Length: 50mm, a classic "normal" lens perspective.
Maximum Aperture: f/1.9, which allows for good low-light performance and shallow depth of field.
Optical Design: Features 6 elements in 4 groups (Gaussian design).
Aperture Blades: 6, contributing to a smooth bokeh.
Minimum Focus Distance: 0.5m (50cm).
Filter Thread Size: 52mm.
Build Quality: Known for its durable, all-metal construction.