Takumar 50mm f/3.5

Notes and sources

Documented from the original Asahiflex Model II manufacturer manual, Takumar interchangeable-lens section. These are the M37 configurations, not later M42 lenses. The manual gives element counts without group counts; missing filter sizes, dimensions and exact production dates have not been inferred. Maker distance scale starts at 2.5ft; metric minimum is rounded. The manual describes the preset configuration at 180g, whereas other references report lighter early barrels. Weight is not generalized to every revision and remains unresolved pending barrel-specific verification.