Canon IV-Sb2

Canon IV Sb2

The Canon IV Sb2, also written Canon IV-Sb2, is a 35mm Leica screw-mount rangefinder camera marketed by Canon Camera Co. in March 1954. It was the improved successor to the Canon IV Sb and represents the final refinement of Canon’s premium bottom-loading IV-series rangefinder design [1].

The camera uses Canon’s universal threaded mount, compatible with the Leica Thread Mount standard, also known as LTM or M39. It accepts Canon screw-mount lenses as well as many Leica-compatible screw-mount lenses, making it directly relevant to LeicaLensList’s rangefinder camera scope [1].

The IV Sb2 retained the combined coincidence rangefinder and reversed Galilean viewfinder of the IV-series cameras, but Canon improved the eyepiece and mechanical ergonomics. The finder can be rotated between three magnifications, commonly interpreted as approximately 0.67x for 50mm, 1.0x for 100mm and 1.5x for 135mm. There are no projected framelines, so the chosen viewfinder magnification determines the approximate field of view [2].

The most important technical change from the IV Sb was the revised shutter system. Canon’s official museum lists a geometric shutter-speed sequence with a slow-speed dial for T, 1, 1/2, 1/4, 1/8 and 1/15 second, and a main shutter-speed dial for X, B, 1/30, 1/60, 1/125, 1/250, 1/500 and 1/1000 second. The shutter is a two-axis, horizontal-travel focal-plane shutter with cloth curtains [1].

Compared with the earlier IV Sb, the IV Sb2 raised the slow-to-fast speed crossover from 1/25 to 1/30 second and introduced the more modern geometric shutter-speed progression. Leica Copies Japan also notes that X-sync moved to the main shutter-speed dial at approximately 1/45 second, while the slow-dial X setting remained for older long-delay electronic flash units [3].

History

Development and Launch

The Canon IV Sb2 was marketed in March 1954 as an improved version of the IV Sb. Canon described it as the successor to the IV Sb and emphasized its precision feel, revised shutter-speed index system, easier two-fold shutter-speed progression and exposure-count reminder at the base of the film advance knob [1].

Production Evolution

Collector research based on Peter Dechert dates production from approximately July 1954 to July 1956, although Canon’s own museum gives March 1954 as the marketing date. Leica Copies Japan notes this as a historical anomaly, because confirmed serial-number evidence below 170000 is limited and the related II-S2, II-D2 and II-F2 models appear more clearly from the 170000 range onward [3].

Serial Number Notes

Serial-number identification should be handled carefully. Leica Copies Japan gives Peter Dechert’s IV-Sb2 range as 122490 to 229000, but found examples are mostly recorded from approximately 17123x to 22893x. For LeicaLensList, the safest approach is to record the broad Dechert range while noting that commonly verified examples cluster later in the range [3].

Naming and “Kai” Listings

Canon now uses the IV Sb2 name, but period documentation did not always treat it clearly as a separate model. Leica Copies Japan notes that Canon often referred to these models as “improved” versions of earlier cameras, and that Japanese sellers may describe the IV-Sb2 as IV-Sb Kai, meaning a modified or improved IV-Sb. For database use, IV Sb2 should remain the main name, while IV-Sb2, IV Sb Kai and Canon 4Sb2 can be stored as alternate search names [3].

Collector Notes

The Canon IV Sb2 should be distinguished from the earlier Canon IV Sb. Key identifiers include the revised geometric shutter-speed sequence, the 1/30 second crossover speed, the two-part main shutter-speed dial with a fixed index after release, the added 1/15 second slow speed, the improved eyepiece, and the exposure-count reminder near the film advance knob [1][3].

It should also be kept separate from the related Canon II-S2, which is essentially a lower-specification companion model without the 1/1000 second top speed. The IV Sb2 remained the top specification camera in this group, combining LTM compatibility, a 1/1000 second shutter, FP/X flash synchronization and Canon’s variable-magnification combined rangefinder-viewfinder system [3].

For collectors, the IV Sb2 is one of the most desirable Canon screw-mount bodies because it represents the peak of Canon’s bottom-loading LTM rangefinders. It is more refined than the earlier IV Sb, but still belongs to the pre-V-series generation before Canon adopted hinged backs, trigger wind systems and later integrated finder designs.

For LeicaLensList, the Canon IV Sb2 should be stored as a separate LTM camera entry, not merged with the Canon IV Sb. Finish details, Japanese “Kai” seller descriptions and lens-kit differences should be treated as metadata or variant notes rather than part of the main model name.

Sources

• [1] Canon Camera Museum. IV Sb2. https://global.canon/en/c-museum/product/film24.html
• [2] Photoethnography.com. Canon IV Series of Rangefinders. https://www.photoethnography.com/ClassicCameras/CanonIV.html
• [3] Leica Copies Japan. Canon IV-Sb2. https://leica-copies-japan.com/Canon.html
• [4] Canon Camera Museum. View by Period, 1946-1954. https://global.canon/en/c-museum/history/story03.html
• [5] Retina Rescue. Canon IVSB2. https://retinarescue.com/canonivsb2.html