Japanese medium-format lenses for Mamiya cameras (1961–1999), engineered for 6×7 cm format with focal lengths from 37 mm to 500 mm and apertures down to f/1.4.
Technical Details
The Sekor lenses are based on various optical constructions: The standard 50mm lenses mostly use 6-7 elements in 4-5 groups, while wide-angle lenses like the 37mm employ retrofocus designs with up to 11 elements. Typical apertures range from f/1.4 for the 80mm portrait lenses to f/8 for the super-telephoto lenses. The filter thread varies between 52mm and 95mm depending on the focal length. The lenses for the RB67 system use leaf shutters with speeds from 1/400s to 1s, while the RZ67 variants offer electronically controlled shutters with speeds up to 1/700s.
History & Development
In 1961, Mamiya introduced the first Sekor lenses for the Mamiya Prismat. In 1970, the introduction of the RB67 marked a turning point with specially developed Sekor-C lenses for the 6x7cm format. In 1982, the RZ67 followed with improved Sekor-Z lenses, which offered multi-layer coating and more precise mechanical tolerances. The last generation, Sekor-NB, was created in 1990 for the RB67 Pro-S system. Production ended in 1999 with the discontinuation of Mamiya's analog systems.
Practical Use in Film
Mamiya Sekor lenses were used in still photography for film productions, particularly for publicity shots and set photography. The 6x7cm format provided sufficient resolution for large-format prints in magazines and posters. Cinematographers like Douglas Slocombe used Mamiya systems in parallel with their film work for location scouting and test shots. The high sharpness of the 127mm f/3.8 lenses made them preferred tools for portrait work of actors.
Comparison & Alternatives
Mamiya Sekor competed directly with Hasselblad Zeiss lenses and Pentax 67 optics in the professional medium format segment. While Hasselblad was constructed more modularly, Mamiya offered integrated shutters and larger image formats. Modern alternatives include Fujifilm GFX lenses or adapted vintage optics on digital medium format cameras. Phase One XF systems have today taken over Mamiya's position in the studio sector but achieve higher resolutions through sensor technology than the original film formats.