35mm film
See the Category: 35mm film.
The 35mm film format uses film with sprocket holes for mechanical advance, wound onto cassettes. This format was introduced to make use of cheaply-available movie film and make small cameras which were easily portable in comparison the the common large-format plate cameras of the time. The prototype Leica, the Ur-Leica is said to be the first 35mm camera, made by Oskar Barnack in 1913. The standard frame size for this format is 24x36mm - twice the size of movie images. Modern cassettes typically have enough film for 12, 24 or 36 frames. 35mm is by far the most widely used photographic film format.
Bulk backs are available for some cameras, aimed at professional use, which allow the photographer to use 100-foot lengths of film at a time, minimizing the inconvienience of having to reload the camera and miss a shot. These were used by some sports photographers, but the digital revolution has largely made bulk backs obsolete.
135 format describes 35mm film preloaded in cassettes that can be loaded in daylight. When 35mm was orginally used by photographers, they salvaged film ends and off-cuts from motion picture stock and had to load their cameras in the dark. Early Leicas (from 1925-) were loaded this way.
When 35mm cassettes where commercially made available to photographers, in 1934, Kodak preloaded the film in cassettes which made the format much more user-friendly, as the photographer could actually see what he was doing as he put the film leader into the take-up spool.
There were other, rival daylight-loading systems, but most of these were minority formats compared to 135. The most successful was the Agfa Karat system, which was introduced for the Agfa Karat cameras in 1936, and was produced until 1963. In 1964 Agfa introduced a 35mm cartridge system, called Rapid, to compete with 126 cartridges. The latest, and likely last rival being APS - which may have succeeded but for the rise of digital.
The frugal photographer can still buy 35mm film in 100-foot lengths and spool his own cassettes. This involves putting the roll of film into a bulk loader. Reloadable cassettes are then filled with film using a crank on the loader. The film is then cut and a leader cut into the tail of the loaded cassette. All this can be done in daylight, hence the loaders are called "daylight loaders".
Trivia:
When it was first introduced in the 1930s, the 35mm format was known as "miniature format".
