35mm Slide Film

with a Frame Size of 24x36 mm

​

Slide film, color reversal film, or transparency film (derived from the Ancient Greek dia, δία, "through") is a photographic film that displays tones and colors in their natural, positive state once processed.

​

Typically, slide films are used to project the captured images onto a screen using a slide projector. For this to happen, the individual frames must first be mounted into slides.

​

A standard roll of 35mm slide film offers 36 exposures, though 24-exposure rolls are occasionally found.

In the processing lab, unmounted film is typically cut into strips of 5 or 6 frames. Up until a few years ago, labs also offered the option to automatically mount the individual slides into cardboard or plastic frames during processing.

 

.

 

For projection, both glassless mounts (as seen in the example below) and glass slide mounts are used. With glass mounts, the slide is sandwiched between two panes of glass, much like a picture hanging on a wall. The main advantage of glass mounts is that they ensure perfect flatness of the film during projection. This prevents the slide from buckling under the heat of the projector lamp, resulting in uniform sharpness across the entire screen.

Disadvantages, however, included the higher cost of these mounts, the risk of trapped dust particles, and the formation of Newton's rings.

To prevent these colorful distortions, slides can be mounted using special Anti-Newton glass (AN glass). Newton's rings (named after Isaac Newton) appear as light-and-dark zones or rainbow-like interference patterns. They occur due to light wave interference within the tiny air gap between two highly reflective, nearly parallel surfaces—specifically, the smooth film base and the glass pane.