In photography , a changing sack is a spacious, light-proof, mostly double-walled fabric sack with also light-proof access openings. This means that light-sensitive material can also be handled in ambient light. Application examples would be:
- The removal of a partially exposed film from the camera, for example if rewinding into the film cartridge is no longer possible due to a film tear or a defective transport mechanism .
- The loading of sheet films into the film cassette of a view camera .
- The loading of a developing tank before processing in the laboratory.