22mm: Difference between revisions

22mm was one of the first film formats available for amateur use, introduced in 1912 for use with the Edison Home Kinetoscope. The format employed a unique system in which the picture was printed in three strips, with the center strip printed in reverse order so that it could be run backwards through the mechanism. The perforations are located between each strip of images. The reel would be cranked forward for the first strip, cranked backward for the second strip, and cranked forward again for the third strip. In order to place the selected strip in the optical path, a knob is turned to shift the lateral position of the gate, drive mechanism, and reel arm assembly, while the lens and lamphouse remain in a fixed position. The Home Kinetoscope was also equipped with a stereopticon lens and slide carriage. To project slides, the lamphouse was pushed away from the operator to align it with the stereoptical lens.

22mm films were printed on a diacetate [[film base]], making the Home Kinetoscope safer to operate than the so-called “toy projectors” that were commonly available for home, which were designed to run short lengths of highly flammable nitrate film. They were distributed on wooden cores and shipped to the user in film cans with a metal post in the center to hold the core in place.