Dark slide (photography)

When used, the dark slide is removed for the period of the exposure and then replaced.

Modern dark slides are used in conjunction with a film holder, that either holds in place pieces of cut sheet film or, if modified, some piece of light sensitive material such as glass.

After the exposure, the dark slide is put back in place and the array is put away, usually in a light tight cloth bag or box until it can be taken into a darkroom for development.

Ordinarily, in modern film holders, the opening to permit the dark slide to be removed is protected by a strip of black velour or other black baffling that permits the dark slide to move in and out of the holder while restraining the amount of light used by the dark slide while either in place or removed.

A dark slide is used for magazine backs on medium format cameras such as Hasselblad and Mamiya, and plate or sheet film holders on view cameras, like the earlier Reisekamera.