See the Category: 126 film. See also 126 film (roll)

The Kodapak 126 film cartridge is a roll film magazine for 35mm-wide film with a paper backing.

It was launched in 1963 by Kodak in answer to consumer complaints about the complications involved with loading and unloading roll film cameras. With the cartridge film, you don't have to attach the film leader to a take-up spool. The cartridge simply drops into the camera. Since the cartridge is asymmetric, it cannot be loaded incorrectly. You close the back, wind, and shoot. 126 cameras have a window to show the back of the cartridge, which is printed with the film details, and has a small hole revealing the frame number printed on the backing paper.

The inventor, Hubert Nerwin, was granted US patent 3,138,081 on June 23, 1964. The patent was assigned to Eastman Kodak.

At the end of the roll, you don't have to rewind. Even if you remove the cartridge in mid-roll, only the current exposure is light-struck; the rest of the film is protected inside the cartridge. 126 cartridges can be reloaded with 135 film in a darkroom.

It also incorporated one of the first widely used mechanical film-speed sensing systems; using notches on the cartridge, a speed of 64, 80, 125 or 160 ASA was indicated and set the camera's exposure mechanism. However, not all cameras took advantage of this feature. Kodak patents decades earlier (for example: 2186611 (1938), 2186613 (1937)) described this innovation.

The film format itself wasn't new and was a way of re-packaging and reviving the ailing 828 roll film format introduced by Kodak in 1935 along with a range of Kodak Bantam cameras. Kodak Instamatic 126 cameras were introduced simultaneously with the 126 films.

126 film is 35mm wide and has a single perforation per frame. The image size is nominally 26×26mm, though actually it is 29×28mm masked to approximately 26½×26½mm. Therefore 126 frames have around 4/5ths of the resolution of 135 35mm frames. The film has pre-exposed borders and exposure numbers. Cameras accepting this film are also called Instamatic cameras (or simply Instamatics), from the name of the first Kodak models taking it, the Instamatic series.

The decline of the format didn't originate from a lack of cameras in circulation but from the fact that 126 cameras were generally cheap, low end units which were easily superseded long before the arrival of the digital era. Some quality 126 cameras were produced including SLRs but they were rare in absolute numbers. The square nature of 126 exposures discouraged their uptake in professional fields and meant film developers often made prints very small to fit within the 4" high photo album threshold of 6x4" prints and to counter the blur caused by the slow shutter speeds and inadequate lenses usually found in these cameras.

126 cartridges were last produced in 2007 by Ferrania with only old (i.e. freezer-preserved) stocks still for sale today. Some are available under Ferrania's own Solaris label while others are sold rebadged as Adox Adocolor Instamatic by Fotoimpex. These cartridges contain ASA 200 film but there are user reports of them having ASA 64 notches.