35mm slide film with a page size of 24x36mm.

As slide film, slide film (from ancient Greek δία dia, German 'through') or reversal film is a photographic film that, after its development, shows gray values ​​and colors in their natural view.

As a rule, slide films are used so that the resulting recordings are projected onto a screen using a slide projector.

To do this, the individual pictures must be framed.

A typical slide film offers 36 pictures in small format, more rarely only 24 pictures.

Slide films are cut into strips of 5 slides in the development laboratory. Until a few years ago it was possible for the laboratory to automatically frame the individual slides.

Frames without glass are used, as can be seen in the example below, but also slide frames with glass surfaces. The slides are framed behind glass, as is also done with pictures that we hang on the wall. The glass surfaces achieve a better flatness during the projection, as this ensures a uniform sharpness of the projection.

Disadvantages were the higher cost of these frames, trapped dust, or Newton's rings.

To avoid these color disturbances, slides can be framed under anti-Newton glasses.

Newton's rings (also Newton's rings, named after Isaac Newton) are light-dark zones or interference colors that are created by interference at the air gap between two reflective, almost parallel surfaces.