Carl Zeiss Jena's Exakta portrait classic — the Biotar 58mm f/2 known for swirly bokeh.
The Carl Zeiss Jena Biotar 58mm f/2 is a standard prime from Jena that became one of the defining lenses of the pre-war and early post-war Exakta system. It is the design that the later Soviet Helios-44 was based upon, and it served as the fast normal lens for Exakta bodies from the late 1930s onward. Its Exakta-fit production dates from around 1936 and it carried on in various guises for many years.
This is a manual-focus Exakta-mount lens with a 58mm focal length and a maximum aperture of f/2. It uses a six-element double-Gauss layout of the classic Biotar type. The aperture is set by hand on the barrel, and on Exakta bodies the lens couples through the mount's internal actuating lever. Coating varies by production year; further construction figures are left out here where they cannot be confirmed for a given serial range.
The Biotar 58mm f/2 is famous among photographers for its swirly bokeh: wide open, out-of-focus highlights toward the edges of the frame smear into a rotating, whirlpool pattern that gives portraits a distinctive spun look. The centre stays sharp while this swirl builds in the surrounds, an effect that many buyers seek out deliberately. It suits portraits and creative general shooting where that character is the point.
This is a genuinely collectible lens and clean Exakta examples command high prices. Because of its age, check carefully for haze, internal fungus, coating scratches and element separation, all of which are common. Confirm the aperture blades are dry and the ring clicks properly, and expect some to have been serviced. Adapting to mirrorless with an Exakta adapter lets modern shooters chase the swirl on digital sensors.