KMZ Helios-44 — Soviet 58mm f/2 standard lens, Zeiss Biotar derivative, M39/M42/K mounts
The Helios-44 is a Soviet standard lens made by KMZ near Moscow, first appearing in 1958 as a derivative of the prewar Carl Zeiss Biotar formula acquired as postwar reparations. It became one of the most widely produced Soviet lenses, fitted as standard on Zenit SLR cameras for decades.
Optically it follows the Biotar's double-Gauss layout, commonly cited as six elements in four groups, with an 8-blade aperture. Early versions used M39 screw mount for Zenit-3 cameras around 1960, shifting to M42 from the mid-1960s as the Helios-44-2, with later K-mount versions such as the Helios-44M-7 for automatic-diaphragm Zenit bodies.
The lens is best known today for a distinctive swirly bokeh at wide apertures, a side effect of the Biotar-derived formula that made it popular for a vintage rendering character on mirrorless bodies via adapters. Wide open it is soft with low contrast, sharpening by f/4.
Helios-44 lenses are extremely common and cheap in the used market thanks to huge Soviet-era production, with M42 examples easiest to find. Check the aperture and preset mechanism move smoothly, look for haze given the age of most examples, and confirm which mount variant is on offer.