Canon IV Sb

Canon IV-Sb

The Canon IV-Sb, also written Canon IV Sb or Canon IVSb, is a 35mm screw-mount rangefinder camera marketed by Canon Camera Co. in December 1952. It was introduced as the successor to the Canon IV-S and became one of Canon’s most important early postwar rangefinder cameras [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].

Canon described the IV-Sb as a high-precision model and highlighted its flash synchronization system. The camera provided both FP and X synchronization through Canon’s side flash rail, making it one of the most advanced screw-mount rangefinders of its period [1][2].

The IV-Sb 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 [1][3].

Mechanically, the Canon IV-Sb 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 and 1/8 second, while the main shutter-speed dial covers X, B, 1/25, 1/40, 1/60, 1/100, 1/200, 1/500 and 1/1000 second [1].

History

Development and Launch

The Canon IV-Sb was marketed in December 1952. Canon positioned it as the successor to the IV-S, adding X-sync for electronic flash while retaining the 1/1000 second shutter and high-grade bottom-loading rangefinder body [1].

The camera was known in some export markets as the Canon IV-S2. Leica Copies Japan notes that IV-Sb was the official factory and domestic-market name, while English-language manuals often used IV-S2 [2].

Production Evolution

Leica Copies Japan, citing Peter Dechert, gives production from approximately December 1952 to March 1955. The same source states that 34,975 Canon IV-Sb cameras were produced, making it one of Canon’s most commercially successful bottom-loading rangefinder cameras [2].

Serial Number Notes

Serial-number identification should be handled carefully. Leica Copies Japan gives the Peter Dechert range as 65760 to 160000, while found examples are recorded from approximately 6757x to 16516x. The safest wording is to use the reported Dechert range while noting that observed examples can extend slightly beyond the clean published upper range [2].

Flash Synchronization

The IV-Sb is especially important because of its simplified electronic flash synchronization. The slow-speed dial includes an X setting, allowing electronic flash synchronization without the more complex delay-setting systems used by some earlier cameras [1][2].

There is some disagreement over the exact X-sync speed. Leica Copies Japan reports approximately 1/15 second according to Peter Dechert, while notes in the Canon Flash Unit Y manual suggest approximately 1/25 second. A cautious database field should therefore use approximately 1/25s X-sync, with 1/15s also reported by collector sources [2].

Relationship to Canon IV-S

The Canon IV-Sb should be kept separate from the Canon IV-S. The IV-Sb is essentially a Canon IV-S with two important additions: a slow-speed shutter dial lock and X synchronization for electronic flash. These features make it a distinct and historically important model rather than a minor finish variant [2].

Relationship to Canon IV-Sb2

The IV-Sb should also be kept separate from the later Canon IV-Sb2. The IV-Sb uses the older shutter-speed sequence with values such as 1/25, 1/40, 1/60, 1/100 and 1/200 second. The IV-Sb2 introduced the revised modern sequence with 1/30, 1/60, 1/125, 1/250 and 1/500 second values, plus internal shutter improvements [2][4].

This distinction is important for identification. A seller title may use Canon IV Sb, IVSB, IV-S2 or 4Sb, but the shutter-speed dials should be checked to confirm whether the camera is the earlier IV-Sb or the later IV-Sb2.

Naming and Identification

The correct main name is Canon IV-Sb. Common alternate names include Canon IV Sb, Canon IVSb, Canon IVSB, Canon IV-S2, Canon 4Sb and Canon IV-Sb Rangefinder. The export name IV-S2 should be treated as an alias for the same base camera [2].

The model name is usually not engraved 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 X marking, and the older shutter-speed sequence with 1/25, 1/40 and 1/100 values.

Collector Notes

The Canon IV-Sb is one of Canon’s most important Leica-compatible screw-mount cameras. It combined strong build quality, a 1/1000 second cloth shutter, FP/X flash synchronization and Canon’s distinctive rotating three-magnification finder in a compact bottom-loading body.

Collectors should check shutter curtains, rangefinder clarity, finder magnification selector, side flash rail, slow-speed dial lock, X-sync marking, base plate, serial number and shutter-speed dial values. Clear photos of the shutter dials are especially useful because the IV-Sb and IV-Sb2 can otherwise look very similar.

The Canon IV-Sb should be treated as a separate LTM camera entry because its X-sync system, export-market importance, production volume and older shutter-speed sequence distinguish it from both the Canon IV-S and the later Canon IV-Sb2.

Sources

• [1] Canon Camera Museum. IV Sb. https://global.canon/en/c-museum/product/film19.html
• [2] Leica Copies Japan. Canon Rangefinder Cameras, Canon IV-Sb / IV-S2. 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. IV Sb2. https://global.canon/en/c-museum/product/film24.html
• [5] Mike Eckman. Canon IV Sb, 1952. https://mikeeckman.com/2019/10/canon-ivsb-1952/