Canon 100mm f/3.5 III

Canon 100mm f/3.5 III

By the time Canon released the 100mm f/3.5 III in March 1960, the company had refined its compact short telephoto into one of the better-regarded Leica thread mount lenses of the era [1]. It carried a five element, four group optical layout, a notable step up from Canon's earliest 100mm screw mount lens, which used a simple triplet at f/4 in a heavy brass barrel[2]. The lens is small and light for its focal length, and its modest size made it a practical travel companion on Leica and Canon rangefinder bodies.

The lens uses a ten blade diaphragm and stops down to f/22, with a closest focusing distance of one meter. It takes 40mm filters and weighs about 220 grams in a barrel roughly 47mm in diameter and 73mm long. As a Leica thread mount lens it is rangefinder coupled and works on LTM bodies as well as on M cameras through a thread to bayonet adapter. Period users note a long focus throw and, on earlier examples, an aperture ring without click stops, both typical of the lens family's late 1950s origins. The lens was sold at an original price of 17,000 yen.

The 100mm f/3.5 went through more than one iteration. The early type closely echoed the Leitz Elmar 90mm f/4 in form, while later versions adopted styling closer to Canon's early SLR lenses, with the later barrel being somewhat larger than the slim early one. Because a separate accessory finder is needed for accurate framing on bodies without 100mm framelines, many lenses are bought and sold together with a dedicated viewfinder and case.

Optical qualities

Rendering Documented impressions of the lens are consistently favorable. One detailed owner account describes it as sharp with pleasant contrast, attractive color rendition, and smooth out of focus areas, and rates its overall image quality above a Leitz Elmar 90mm f/4 used alongside it. The same source compares its color and monochrome character to that of a Leitz Summitar. These are individual observations rather than measured test data, but they align with the lens's general reputation among rangefinder users.

Collector and user notes The most common practical complaint concerns the original matching viewfinder, which is solidly made but small and somewhat difficult to use, particularly for moving subjects; substituting a brightline finder intended for a 100mm or 105mm lens is a common workaround. On a Canon P, whose finder already includes 100mm framelines, no external finder is required.

History

Development and Launch The 100mm f/3.5 III was marketed from March 1960 as part of Canon's S series of Leica thread mount lenses. It descended from Canon's earlier 100mm screw mount telephotos, the first of which was a triplet of f/4 maximum aperture built in the heavier early Canon barrel style, with the f/3.5 five element design representing a later and optically more ambitious approach.

Production Evolution Across its production the 100mm f/3.5 appeared in successive versions. The earlier type was slim and Elmar like in appearance, while later barrels grew larger and took on styling related to Canon's early SLR optics. The five element, four group formula and the 100mm f/3.5 designation carried through, with the changes centering on barrel form and external styling rather than a change of focal length or speed.

Collector Notes Buyers should confirm which version they are looking at, since the early slim barrel and the later larger barrel differ in handling and finder needs, and verify that any included accessory finder and case match the lens. As with most coated lenses of this age, internal haze and coating condition are worth checking before purchase. Note that LeicaLensList records the production span as starting in 1960 with no confirmed end date; published references generally treat the f/3.5 line as a discontinued vintage product rather than a current one.