Zeiss Biotar optical formula

Helios-44 is a Soviet copy of the Carl Zeiss Biotar 58mm ƒ/2 lens produced under the Helios lens brand.^[1] The lens is currently made in Russia for the M42 lens mount.

Specification

• Distance scale: 0.5 m to ∞
• Aperture: f/2 - f/16
• Focal Length: 58 mm
• Mount: M39, M42, Pentax-K, Zenit-D, Canon EF
• Mount thread for Attachments: M52 x 0.75
• Weight: 230 g
• Resolution: 50/30 lines per millimeter