In this so-called 'digital age', there is still something magical about the 8mm film format Kodak developed in 1932, as a solution for home movies.
It was called 'Standard 8mm' back then and was actually 16mm film with twice as many perforations (as regular 16mm) along each side. The film was loaded into a camera, exposed along half its width, flipped and exposed along the other half. In processing, the film was slit down the middle; the result was two lengths of 8mm film, each with a single row of perforations along one side - and four times as many frames as 16mm film.