More popularly referred to as 35 mm film, the film is a format of photographic film used for still photography. It is a film with a film gauge of 35 mm (1.4 in) loaded into a standardised type of magazine – also referred to as a cassette or cartridge – for use in 135 film cameras. The engineering standard for this film is controlled by ISO 1007 titled '135-size film and magazine'.[1]
The term 135 was introduced by Kodak in 1934[2] as a designation for 35 mm film specifically for still photography, perforated with Kodak Standard perforations. It quickly grew in popularity, surpassing 120 films by the late 1960s to become the most popular photographic film size. Despite competition from formats such as 828, 126, 110, and APS, it remains so today.
The size of the 135 film frame with its aspect ratio of 1:1.50 has been adopted by many high-end digital single-lens reflex and digital mirrorless cameras, commonly referred to as "full-frame". Even though the format is much smaller than historical medium format and large format film, it is much larger than image sensors in most compact cameras and smartphone cameras.