Reversal Film

In photography, a reversal film is a type of photographic film that produces a positive image on a transparent base. The film is processed to produce transparencies or diapositives (abbreviated as diafilm in many countries) instead of negatives and prints. Reversal film is produced in various sizes, from 35 mm roll film to 8×10" sheet film.

A slide is a specially mounted individual transparency intended for projection onto a screen using a slide projector. This allows the photograph to be viewed by a large audience at once. The most common form is the 35 mm slide, with the image framed in a 2×2" cardboard or plastic mount. Some specialized labs produce slides from digital camera images in formats such as JPEG, and also work with computer-generated presentation graphics and make slides from images such as fingerprints, microscopic sections, paper documents, astronomical images, etc.

Reversal film is sometimes used as motion picture film, mostly in the 16 mm, Super 8 and 8 mm formats, to yield a positive image on the camera original. This avoids the expense and slight degradation of image quality resulting from using a negative film, and copying to a positive, to produce a print for projection.