Famous 13 blades Helios 44 58mm f/2 2/58mm, Excellent Rare Lens Zenit. This lens was designed at Krasnogorsky Mechanical Plant.
This is a representative of vast "Helios-44" family, that was based on German Carz Zeiss Jena Biotar 2/58. Firstly it has a name "BK" - Biotar from Krasnogorsk. Optical scheme was calculated in 1951 at State Optical Institute (USSR). This is one of the most popular lenses in the world.
This lens was default for SLR cameras "Zenit-3", "Zenit-3m", "Crystal" and optional for "Zenit" and "Zenit-C". This lens had either 8, or 13 aperture blades. Early lenses had ...