# Helios 44-2 58mm f/2

- Brand: KMZ / Valdai / Jupiter (USSR)
- Mount: M42
- Focal length: 58mm
- Max aperture: f/2
- Optics: 6 elements / 4 groups
- Min focus: 0.5 m
- Filter thread: 52mm
- Production: c. 1967-1992

The most produced lens on the mount and the swirl-bokeh king: a Soviet Biotar derivative made by the million across several factories. Factory marks and serial prefixes are their own collecting field.

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Source: ShutterFile (https://shutterfile.com/m42/helios-44-2/). Production dates are catalog-era approximations (c. = circa); independent reference, not affiliated with any manufacturer.