Canon IV Sb

Canon IV Sb

The Canon IV Sb is a 35mm Leica screw-mount rangefinder camera marketed by Canon Camera Co. in December 1952. It belongs to Canon’s early IV-series rangefinders and is one of the company’s most important pre-V-series screw-mount bodies. Canon’s own museum describes it as a historic model in Japan’s camera history and highlights its combined FP-sync and X-sync flash capability [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. For LeicaLensList classification, the mount should therefore be listed as LTM [1].

The Canon IV Sb follows the Barnack-style bottom-loading rangefinder layout, but it adds several Canon-specific refinements. It has a combined coincidence rangefinder and viewfinder, using a reversed Galilean optical system that can be rotated between three magnifications. Photoethnography describes the finder settings as approximately 0.67x for 50mm, 1.0x for 100mm and 1.5x for 135mm. There are no projected framelines, so the finder magnification itself determines the approximate field of view [3].

Mechanically, the 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 high-speed dial covers X, B, 1/25, 1/40, 1/60, 1/100, 1/200, 1/500 and 1/1000 second. Film loading is by removable baseplate, and film advance and rewind are both operated by top-mounted knobs [1].

Canon’s published dimensions and weight are 140 × 72.2 × 67 mm and 790 g with Canon 50mm f/1.8. Body-only weight is reported by Mike Eckman at approximately 510 g, but Canon’s official museum value includes the standard lens kit and should be treated as the factory-published reference value [1][4].

History

Development and Launch

The Canon IV Sb was developed as the successor to the Canon IV S. Leica Copies Japan describes it as essentially an IV S with two important additions: a slow-speed shutter dial lock and an X-sync setting for electronic flash [2]. This made the IV Sb a major step in Canon’s attempt to compete seriously with Leica screw-mount cameras in both domestic and export markets.

Production Evolution

Production is generally dated from December 1952 to March 1955. Leica Copies Japan, citing Peter Dechert, gives total production as 34,975 cameras, making the IV Sb one of Canon’s most successful early rangefinders and one of the models that established Canon’s credibility outside Japan [2]. Photoethnography gives the same production period and approximately 35,000 examples [3].

Export Naming

The official domestic and factory name was Canon IV Sb, but export-market documentation often used the name Canon IV-S2. Leica Copies Japan notes that English-language manuals commonly refer to the model as IV-S2 rather than IV Sb [2]. For LeicaLensList, the main database name should remain IV Sb, with IV-S2 stored as an alternate or export name.

Serial Number Notes

Serial-number identification should be handled carefully. Leica Copies Japan gives the Peter Dechert serial range as 65760 to 160000, while found examples are recorded from approximately 6757x to 16516x [2]. This means the broad serial information should be treated as a reported collector range rather than a factory-verified continuous production block.

Flash Synchronization

The IV Sb is strongly associated with Canon’s early flash synchronization system. Canon states that FP-sync and X-sync were provided through a direct synchronization system with the flash rail [1]. Leica Copies Japan notes that the X-sync speed is debated, with Peter Dechert giving approximately 1/15 second, while Canon Flash Unit documentation has been interpreted as approximately 1/25 second [2]. For database purposes, approximately 1/25s X-sync, disputed is the safest concise field entry.

Collector Notes

The Canon IV Sb should be distinguished from the earlier IV S and the later IV Sb2. The IV Sb has the X mark on the slow-speed dial, a slow-speed dial lock, a 1/1000s top speed and the earlier shutter-speed progression. The later IV Sb2 introduced a revised shutter sequence, a non-rotating high-speed dial and other improvements, so it should be treated as a separate model [2][3].

Collectors should check the slow-speed dial, X-sync marking, side flash rail, finder magnification selector, serial number, export markings and whether the camera is described as IV-S2 in accompanying documentation. The model is valued because it combines Leica screw-mount compatibility with Canon’s variable magnification finder and historically important flash synchronization system.

For LeicaLensList, the Canon IV Sb should be stored as an LTM camera. The export name IV-S2, flash-sync notes and lens-kit variations should be stored in metadata or description fields rather than changing the main model name.

Sources

• [1] Canon Camera Museum. IV Sb. https://global.canon/en/c-museum/product/film19.html
• [2] Leica Copies Japan. 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] Mike Eckman. Canon IV Sb, 1952. https://mikeeckman.com/2019/10/canon-ivsb-1952/
• [5] CameraManuals.org. Canon II-D / IV-S2 Manual. https://www.cameramanuals.org/canon_pdf/canon_ii_d_iv_s2.pdf