The film itself has the same dimensions and perforations as the 35mm movie film but is enclosed in a light-tight cartridge to allow cameras to be loaded in daylight. The standard image format is 24 x 36 mm. Other image formats were also used, like the half-frame format of 18 x 24 mm that earned some popularity during an era of unusually high film costs in the 1960s and the 24 x 24 mm of the Robot cameras. Odd formats include the 24 x 32 mm and 24 x 34 mm on the early Nikon rangefinders, and 24 x 23 mm for use with stereo cameras. In 1998, Hasselblad introduced a 24 x 65 mm panoramic format with the XPan camera. There is also a 17x17mm format used by Tessina subminiature camera.
The film is housed in a single spool metal cartridge, where the film is wound on an internal bobbin and exits via a velvet covered slot. The end of the film is cut on one side to form a leader, which is to be inserted into a correspoding slot in the cameras take up spool.
The film is available in lengths for varying numbers of exposures. The standard full-length roll has always been 36 exposures (assuming a standard 24x36 frame size). Through about 1980, 20 exposure rolls were the only shorter length with widespread availability. Since then, 20 exposure rolls have been largely discontinued in favor of 24 and 12 exposure rolls. Other, mostly shorter lengths have been manufactured, mainly as marketing gimmicks. For example, there have been some 6, 8, and 10 exposure rolls given away as samples or sold to insurance adjustors for use in documenting damage claims. Users who load their own rolls can use any length of film that will physically fit in the cartridge; with thinner emulsions up to 45 exposures will fit.
Ordinarily, the film must be rewound before the camera can be opened. Some newer cameras wind the film fully upon loading and then expose the images in reverse order.
On modern cartridges, the surface contains a pattern called DX encoding that most new cameras use for sensing the film speed and other parameters.
The camera that introduced the format, and also proved that a format this small was suitable for professional photography was the Leica.
In the earliest days, the photographer had to wind 35mm film film into reusable cartridges himself, and cut the film leader. In 1934, Kodak introduced the 135 single use cartridges as we know it today. It was the invention of Nagel Camerawerk in Stuttgart, and Kodak was so interested in this invention that it bought the entire company, and marketed the Nagel camera as the Kodak Retina.
Kodak launched 135 Kodachrome color film in 1935. Agfa followed with the introduction of Agfacolor-Neu in 1936.
The designations 235 and 435 refer to 35 mm film in daylight loading spools, that could be loaded into Leica or Contax style reusable cartridges without need of a darkroom. The 335 was a daylight loading spool for the 24 x 23 mm stereo format.
In the early 1960s, the Nikon F SLR system camera lifted the state of the art for this format to new heights.
The DX encoding system was introduced in the 1980s.
International standard: ISO 1007
See also: 35mm filmHistory