A changing bag is a photographic bag specifically designed to be light-proof while in use. It is required for certain applications involving photosensitive materials when a darkroom

Darkroom

A darkroom is a room that can be made completely dark to allow the processing of light sensitive photographic materials, including photographic film and photographic paper. Darkrooms have been created and used since the inception of photography in the early 19th century...

 is not available, like in the field. Common usages include removing film

Photographic film

Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...

 from its canister to put it into a developing tank, or loading and unloading sheet film holders. They are also commonly found on the set of a film

Film

A film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects...

, where the clapper loader

Clapper loader

A clapper loader, or second assistant camera is part of a film crew, whose main functions are that of loading the raw film stock into camera magazines, operating the clapperboard at the beginning of each take, marking the actors as necessary, and maintaining all records and paperwork for the...

 may need one if shooting on location or far away from a darkroom.

Usage

It is handy to use when a darkroom

Darkroom

A darkroom is a room that can be made completely dark to allow the processing of light sensitive photographic materials, including photographic film and photographic paper. Darkrooms have been created and used since the inception of photography in the early 19th century...

 is not available as is often the case in field shooting. It is also used in commercial photoprocessing labs, often to change paper

Photographic paper

Photographic paper is paper coated with light-sensitive chemicals, used for making photographic prints.Photographic paper is exposed to light in a controlled manner, either by placing a negative in contact with the paper directly to produce a contact print, by using an enlarger in order to create a...

.

Description

A changing bag has two sleeves at one end for both the user's arms, and a zipper (often more than one, for double layered changing bags) to insert the tools and film needed. There are several sizes available, from smaller ones for many still photography

Still photography

Still photography may refer to:* unit still photographer, a person who creates still photographic images for the publicity of films and television programs* other photography producing still images...

 applications to larger bags used in large-format still photography or filmmaking, which may need to hold both a magazine

Camera magazine

A camera magazine is a light-tight chamber or pair of chambers designed to hold and move motion picture film stock before and after it has been exposed in the camera...

 and a can of film stock

Film stock

Film stock is photographic film on which filmmaking of motion pictures are shot and reproduced. The equivalent in television production is video tape.-1889–1899:...

which each have a 1000 foot capacity. Larger changing bag sizes are also available as "changing tents", where the top of the bag can be held in a dome-like configuration through the use of two curved rods.