Bi-pack

-Bi-pack - combination of two films, differently sensitized, but exposed as one.
-Bi-refringence - splitting of light passing through certain kinds of crystals into two rays at polarized right angles to each other.

Initially a system that used frame sequential photography and projected through additive synthesis, Prizma was refined to bi-pack photography, with two strips of film (one sensitized for red and one for blue) threaded as one through the camera.

See also: Plate, Normal, Sharp, Space, Main