Canon 50mm f/2.8 III

Canon 50mm f/2.8 III

The Canon 50mm f/2.8 III is the third and final version of Canon's compact f/2.8 standard lens for Leica-thread rangefinder cameras. Canon marketed it in February 1959 as a relatively affordable normal lens: the official launch price was 10,000 yen, below the 16,000-yen prices listed for both earlier versions.

Optical design

Canon specifies four elements in three groups, a maximum aperture of f/2.8, and a minimum aperture of f/22. The closest focusing distance is 1 metre. Canon's surviving specification page does not state the diaphragm-blade count, so that value should not be inferred from another version or from an incomplete photograph.

The simple four-element layout was not unique to the third version. Canon collector references describe all three 50mm f/2.8 models as variations on the same basic formula, with most of the visible evolution taking place in the mechanical package. That makes the III part of a continuous family rather than a wholly new high-speed design.

Rendering

At 50mm, the lens gives a normal perspective on 35mm film and full-frame digital cameras. Its f/2.8 maximum aperture offers less subject isolation and low-light latitude than Canon's contemporary f/1.8, f/1.5, and f/1.2 standards, but it also permitted a smaller, lighter barrel.

Reliable version-specific optical tests are scarce. It is therefore safer to describe the III by its documented construction and intended role than to promise a particular level of sharpness, contrast, flare resistance, or bokeh. Sample variation, haze, cleaning marks, and rangefinder calibration can have a larger effect on present-day results than period catalogue specifications suggest.

History and versions

Canon introduced the first 50mm f/2.8 in January 1955. That version used the same four-element, three-group count, stopped down to f/16, accepted 34mm filters, and had a distinctive black-and-chrome “zebra” finish. Version II followed in November 1957 with a 40mm filter thread, an f/22 minimum aperture, and styling closer to Canon's other rangefinder lenses.

Version III arrived in February 1959. Canon lists the same 48 × 39.3mm maximum diameter and length as version II, but a weight of 159g rather than 143g. The official I, II, and III designations are the safest way to separate catalogue generations; sellers do not always identify the version correctly.

Handling

The III measures 48mm in maximum diameter and 39.3mm in length, weighs 159g, and takes 40mm filters. Its one-metre minimum focus is conventional for a late-1950s coupled rangefinder standard lens. The all-metal manual controls keep the lens compact on Canon screw-mount bodies and on Leica-thread cameras from other manufacturers.

Condition matters. Check that the focusing cam moves smoothly, that the aperture closes evenly, and that the optical cell is free from haze or separation. A clear lens with accurate rangefinder coupling is more useful than a cosmetically cleaner example whose cam or helicoid is out of adjustment.

Compatibility

This is a native Leica thread mount rangefinder lens with rangefinder coupling. It can be used directly on compatible LTM/L39 rangefinder bodies. On a Leica M body it requires the correct 50/75mm LTM-to-M adapter. A screw thread alone does not guarantee accurate focus: the camera, adapter, and lens cam must all be within calibration.

Collector notes

Version III is historically interesting as the last of Canon's three f/2.8 normal lenses and as a compact alternative to the faster standards that increasingly dominated Canon's late rangefinder period. Its strongest identifiers are the 1959 catalogue position, 40mm accessory thread, 48 × 39.3mm dimensions, and 159g official weight.