Zuiko

Zuiko (Japanese: ズイコー or 瑞光) is a brand of optical lenses made by OM System and previously Olympus Corporation used in the Micro Four Thirds and Four Thirds system. The name Zuiko (瑞光) means 'Holy Light', using a character from the Mizuho Optic Research Laboratory (瑞穂光学研究所), where the lens was developed, and a character from Takachiho Corporation (高千穂製作所), which would eventually become the Olympus Corporation.

With the introduction of the Micro Four Thirds system in 2008, new lenses for that system started to be branded as M.Zuiko Digital.

Optical formula nomenclature

For lenses manufactured until approximately 1972, the number of optical elements of the lens, angle of view, and diaphragm operation could be distinguished by the markings engraved on the lens. The engraving dropped the number of elements with the advent of multicoating, which occurred during the production of OM system lenses. Ace, Pen-F, FTL, and early OM system lenses carry the letter prefix denoting the number of optical elements. Later OM system lenses (generally all multicoated) omitted this prefix.

Notes

For example, an "Olympus OM-SYSTEM G.Zuiko Auto-S 1:1.4 f=50 mm" is a lens with a 'Standard' focal length and a maximum aperture of f/1.4 featuring a seven-element construction and an automatic diaphragm, built for the OM-system. The use of 'standard' refers to the focal length compared to the diagonal dimension of the imager; in this case 50 mm is approximately the diagonal dimension of the 35 mm film frame. 'Wide-angle' lenses have focal length significantly shorter than the diagonal dimension, while 'Telephoto' lenses have focal length significantly greater than the diagonal dimension.