Canon IV-Sb2

Canon IV-Sb2

The Canon IV-Sb2, also written Canon IV Sb2 or Canon IVSb2, is a 35mm screw-mount rangefinder camera marketed by Canon Camera Co. in March 1954. It was introduced as the improved successor to the Canon IV-Sb and represents one of Canon’s most advanced bottom-loading screw-mount rangefinders [1][2].

The camera uses Canon’s universal threaded mount, compatible with the Leica Thread Mount standard, also known as LTM, M39 or Leica screw mount. It accepts Canon screw-mount lenses as well as other compatible 39mm screw-mount rangefinder lenses [1][2].

The IV-Sb2 kept the high-grade construction and combined finder concept of the IV-Sb, but updated the shutter-speed sequence. The most visible technical change was the move from the older 1/25 second crossover sequence to a newer geometric progression with 1/30 second as the crossover speed [2].

The camera uses Canon’s combined coincidence rangefinder and reversed Galilean viewfinder system. The finder can be rotated between three magnifications, commonly interpreted as approximately 0.67x for 50mm, 1.0x for 100mm and 1.5x for critical rangefinder focusing. There are no projected framelines, so the selected finder magnification determines the approximate field of view [3].

Mechanically, the Canon IV-Sb2 uses a two-axis, horizontal-travel focal-plane shutter with cloth curtains. Canon lists the slow-speed dial as T, 1, 1/2, 1/4, 1/8 and 1/15 second, and the main shutter-speed dial as X, B, 1/30, 1/60, 1/125, 1/250, 1/500 and 1/1000 second [1].

The camera provides both FP and X flash synchronization through Canon’s side flash rail. Collector references describe X-sync as approximately 1/45 second on the main dial, with an additional slow-dial X setting around 1/30 second for older electronic flash units [2].

History

Development and Launch

The Canon IV-Sb2 was marketed in March 1954 as an improved version of the Canon IV-Sb. Canon’s official history describes it as especially significant among the postwar Canon rangefinders, and the official camera entry lists it as a March 1954 model with 50mm f/1.5 or 50mm f/1.8 lens options [1][4].

Production Evolution

Leica Copies Japan, citing Peter Dechert, gives production from approximately July 1954 to July 1956. This creates a small dating tension with Canon’s official March 1954 marketed date. For a release-year field, 1954 is the safest value [1][2].

Serial Number Notes

Serial-number identification should be handled carefully. Leica Copies Japan gives the Peter Dechert range as 122490 to 229000, while found examples are recorded from approximately 17123x to 22893x. The same source notes uncertainty about the lower serial numbers from 122490 to 169999, because observed IV-Sb2 examples below 170000 are difficult to confirm [2].

The safest wording is 122490 to 229000, reported Dechert range, with found examples around 17123x to 22893x. Individual listings should be checked against shutter-speed layout, X markings and body features rather than serial number alone.

Relationship to Canon IV-Sb

The Canon IV-Sb2 should be kept separate from the Canon IV-Sb. The earlier IV-Sb uses the older shutter-speed sequence with 1/25, 1/40 and 1/60 second values, while the IV-Sb2 uses the revised sequence with 1/30, 1/60 and 1/125 second values. The IV-Sb2 also moved X-sync to the main dial while retaining a slow-dial X setting for older flash units [2].

Relationship to Canon II-S2, II-D2 and II-F2

The IV-Sb2 formed the top model of Canon’s revised “2” generation. The Canon II-S2 is closely related but lacks the 1/1000 second top speed. The Canon II-D2 removes flash synchronization and side-rail features, while the Canon II-F2 provides FP flashbulb synchronization only. These models can look similar, so the shutter-speed dials, X markings, flash rail and top speed should be checked carefully [2].

Naming and Identification

Canon’s naming around the IV-Sb2 can be confusing. Canon now lists the model as IV Sb2, while collectors and sellers may write IV-Sb2, IVSb2, IV SB2, 4Sb2 or IV-Sb Kai. Japanese seller wording such as Kai usually means modified or improved, and should be treated as title wording rather than part of the main model name [2].

The model name is not usually marked prominently on the body. Important identifiers include the universal threaded lens mount, side flash rail, no self-timer, three-magnification finder, 1/1000 second top speed, slow-speed dial with 1/15 and X positions, and main shutter-speed dial with 1/30 and X positions.

Collector Notes

The Canon IV-Sb2 is widely regarded as one of Canon’s finest bottom-loading screw-mount rangefinder cameras. It combines high build quality, LTM compatibility, 1/1000 second shutter speed, FP/X flash synchronization, variable finder magnification and the compact Leica-style body layout.

Collectors should check shutter curtains, slow-speed operation, rangefinder clarity, finder magnification selector, side flash rail, base plate, serial number and shutter-speed dial markings. The difference between IV-Sb and IV-Sb2 is subtle in photos, so clear views of the shutter dials are especially useful for correct identification.

The Canon IV-Sb2 should be treated as a separate LTM camera entry because its revised shutter-speed sequence, 1/1000 second specification and relationship to the later “2” generation make it distinct from the earlier Canon IV-Sb.

Sources

• [1] Canon Camera Museum. IV Sb2. https://global.canon/en/c-museum/product/film24.html
• [2] Leica Copies Japan. Canon Rangefinder Cameras, Canon IV-Sb2. https://leica-copies-japan.com/Canon.html
• [3] Photoethnography.com. Canon IV Series of Rangefinders. https://www.photoethnography.com/ClassicCameras/CanonIV.html
• [4] Canon Camera Museum. View by Period, 1946–1954. https://global.canon/en/c-museum/history/story03.html