Canon 50mm f/1.8 I

Canon 50mm f/1.8 I

This lens marks Canon's first 50mm f/1.8 standard optic, introduced under the Serenar name in November 1951 for the company's Leica thread mount rangefinders [1]. Canon described it as a notable design in modern optical history, crediting it with controlling the coma-induced flare that troubled earlier Gauss-type lenses, and treating it as a foundation for later large-aperture wide angle and telephoto designs. It arrived during Canon's transition away from the Serenar branding toward the Canon name, so early production overlapped that change [2]. Among collectors it is valued as an affordable and compact alternative to Canon's faster 50mm f/1.4 and f/1.2 screw-mount lenses [3].

The optical formula is a six-element, four-group double Gauss layout, the same general family that underlies the Zeiss Biotar and Planar lenses. The aperture is set by a ring near the front of the barrel that clicks into detents and stops down to f/16 using ten blades. Focusing is handled by a ring at the rear, with a minimum focus distance of one metre and an infinity lock that engages automatically at the infinity setting. The lens is rangefinder coupled and uses the 39mm Leica thread mount, so it can be fitted to Canon and Leica screw-mount bodies directly and to Leica M cameras or mirrorless bodies through adapters. Reviewers note the comparatively long focus throw and the standard one-metre close limit as the main handling traits to adjust to.

The original lens was an all-chrome barrel, sometimes called the Type 1, and later production introduced black-and-chrome finishes. Users report that the optics were carried forward with refinements, with later aluminium-chassis versions said to use somewhat improved coatings over the earlier chrome and brass Serenar examples, although the basic optical design remained the same. The lens was commonly sold alongside Canon rangefinder bodies and often came with matching chrome lens caps.

Optical qualities

Rendering Reviewers describe the lens as sharp with a distinctive look, while corner sharpness drops somewhat at wider apertures before cleaning up by around f/4. Contrast is on the lower side, which is typical of a lens of this era, and the lens gives clear separation between subject and background. Vignetting is reported as not very pronounced. On digital bodies, users note good sharpness and color rendition and a character often described as suited to a film-like look.

Collector and user notes Internal haze is a frequently cited problem, particularly on later examples, and is often attributed to lubricant outgassing in the aluminium-barrel versions, whereas the earlier chrome and brass Serenar lenses are said to suffer it less. Buyers commonly encounter copies affected by haze, fungus, or both, so glass condition should be checked carefully.

History

Development and Launch The Serenar 50mm f/1.8 I was marketed in November 1951 at an original price of 26,000 yen. It appeared as Canon was shifting from its earlier Serenar lens branding, established after the company began making its own lenses in the late 1940s, to the Canon name in the early 1950s, and lenses from this transitional period sometimes carried both markings. The f/1.8 standard lens was produced through the 1950s and is associated with the designer Hiroshi Ito.

Production Evolution Successive rigid-barrel versions of the f/1.8 followed the original through the late 1950s. The earliest lenses were all chrome, and later runs added black-and-chrome finishes and, by user accounts, moved to an aluminium chassis with improved coatings while keeping the six-element double Gauss formula.

Collector Notes The original chrome version is identifiable by its all-chrome barrel and was typically supplied with matching chrome caps. When evaluating a lens, the main concerns are internal haze, fungus, and cleaning marks, since many surviving examples show some degree of these issues. The official Canon Camera Museum specification lists a 40mm filter diameter, a weight of 270 g, and a length of about 36.8mm, which differ slightly from some other recorded values, so buyers comparing references should expect minor variation between sources.