A camera specially constructed to cool the film or plate during an exposure, in order to reduce reciprocity failure; also known as a cooled camera. Temperatures down to −78°C are achieved by keeping dry ice (solid carbon dioxide) in contact with the back plate of the camera, against which the film is pressed. A thick window is needed to insulate the film from the atmosphere. Alternatively, the insulation may be provided by a chamber with an optical window, either evacuated or filled with dry nitrogen gas. Some types of CCD camera are used with nitrogen gas to increase sensitivity and reduce noise.
Subjects: Astronomy and Astrophysics.