Oskar Barnack himself moved from Carl Zeiss to Leitz Wetzlar in 1911, where he began the Leica Story. 20 years later, Zeiss announced their own 35 mm camera and became a direct competitor in the photo market with the introduction of the CONTAX in 1932. Nevertheless, the relation of both companies was always respectful. As a particular example for that, the few cases of a direct cooperation can be considered. Zeiss first announced the 15 mm Hologon f/8 as a lens fixed to the body with a modified Contarex camera. From 1972, Zeiss also manufactured it for Leitz in a Leica M mount. In the Leitz catalogue it was offered as “Carl Zeiss Holog for Leica M” until 1975. The Hologon was a lens with 110° angle of coverage, designed as a three element system only with two thick negative meniscus elements in the front and back, as well as a converging element in the center. As a lens almost without distortion, it did show slight vignetting, compensated with a special centrally graduated density filter. A large bright-line finder with waist-level controls was part of the Hologon outfit as well. The lens was produced in very small numbers only; it is a rarity to find a complete set in good condition today.