A darkroom is a workshop used by photographers working with photographic film to make prints and perform other associated tasks. It is a room that can be made completely dark to allow the processing of photographic materials sensitive to light, including film and photographic paper. Several equipment is used in the darkroom, including an expander, baths containing chemicals and running water. Dark rooms have been created and used since the beginning of photography at the beginning of the 19th century. The dark rooms have many manifestations, from the elaborate space used by Ansel Adams to a redesigned ambulance car used by Timothy H. O'Sullivan. From the initial development to the creation of impressions, the dark camera process allows complete control over the medium.
Due to the popularity of colour photography and the complexity of colour film processing (see process C-41) and the printing of colour photographs as well as the emergence, first of Polaroid technology and subsequent digital photography, Dark halls are declining in popularity. Campus colleges, schools and in the studios of many professional photographers. In most dark rooms, an enlarger, an optical device similar to a slide projector, which projects the image of a negative onto a base, finely controls the focus, intensity, and duration of light, is used for print. A sheet of photographic paper is exposed to the enlarged image from the negative. When making black and white prints, security lighting is commonly used to illuminate the work area. Since most black and white papers are sensitive only to blue, or to blue and green light, a red or amber light can be used safely without exposing the paper.
Color printing paper, which is sensitive to all parts of the visible spectrum, must be kept in total darkness until the prints are properly fixed. Another use for a dark room is to load the film in and out of cameras, development reels, or film mounts, which requires complete darkness. For lack of a dark room, a photographer can make use of a change bag, which is a small bag with arm holes with cuff specially designed to be completely light-proof and used to prepare the film before exposure or the development.