Lens Lab
    Cosinon 55 mm f/ 1.2 Auto (Tomioka)
    Cosinon 55 mm f/ 1.2 Auto (Tomioka)

    Cosinon 55 mm f/ 1.2 Auto (Tomioka)

    55mm · f/1.2

    Overview

    The Cosinon 55mm f/1.2 Auto (Tomioka) is a vintage M42 lens known for its fast aperture and collectible status. Optically, it is soft wide open with low contrast, though it sharpens when stopped down. Its distinctive bokeh features elliptical highlights due to an unusual rear element shape. Build is solid and lightweight at 241g, but the lens contains mildly radioactive thorium glass that may yellow over time. It suits photographers seeking a unique character lens for wide-open shooting, but those prioritizing sharpness may prefer modern alternatives.