The Carl Zeiss Jena Biotar 75 mm f/ 1.5is a legendary fast portrait lens for cameras with the Exakta bayonet and the m42 screw mount. The later version of the lens is equipped with the aperture preset ring and looks different outwardly.
Its optical scheme it is similar with the Gelios-40, however, the Carl Zeiss Jena Biotar 75 mm f/1.5 is sharper with the aperture wide open; there is no decrease of resolution at the center of the frame. The background blurring is more explicit.
Due to a high-quality build, the Carl Zeiss Jena Biotar 75 mm f/ 1.5 can be purchased in an excellent condition. The price for the lens with the m42 screw mount is considerably different.