The polaroid camera is also known as the ‘instant camera’ because it takes pictures and develops them in a matter of minutes. It was invented by Edwin H. Land of the United States and the first polaroid camera was sold in 1948. At that stage, it took only black and white photographs. Later, another camera was built that could take pictures and develop colour photographs.
Polaroid cameras are loaded with a double picture roll. One part is a negative roll of the film, and the other a positive roll of a special printing paper. Small pods (containers) of chemicals are joined to the positive roll. After exposure to light through the camera’s lens, the negative and positive rolls are made to pass through a pair of rollers that break the chemical pods. The chemicals flow over the exposed portion of the negative roll and develop a negative image on the roll – the parts of the picture that should be black are white, and the parts that should be white are black. More chemical reactions take place between the pod chemicals and the chemicals coated on the positive roll, and a positive photograph is made – the white areas in the photograph are printed white and the black areas black. This process takes about 10 seconds for a black and white photograph and upto a minute for a colour one.
When the film is exposed to light, during the photograph, particles of a silver salt in the film are reduced by light to metallic silver. After the photo has been taken, a chemical is released which dissolves dyes in the film. These dyes diffuse upwards. When the dyes reach parts of layers containing metallic silver particles, they get oxidized and are fixed. But the dyes continue to diffuse upward, through parts of layers where the silver salt has not been reduced to metallic silver, until they reach the image-receiving layer. White light from the photographed subject stops all the dyes diffusing. Areas exposed to coloured light from the subject stops some dyes, but not other, and so it appears coloured in the photograph. Areas which receive no light stop none of the dyes, but the dyes combine to become black. The polaroid photograph is a true positive image of the photographed subject.
In 1972 Land introduced an improved ‘pocket model’ of his camera. In this camera, the photographic process is automatically controlled by tiny electronic circuits. About a second after pressing the shutter button, which opens and closes the aperture of the camera, a dry plastic square comes out of the camera. It develops quickly into a colour print.
In 1978 Land introduced an instant home movie system, called polar vision. In this system, movie films can be shown on the special projector just a few minutes after they are exposed.
Polaroid camera is a wonderful camera and is being used by mature photographers all over the world. During the recent years, the use of polaroid cameras has gone into scientific world for taking the oscilloscopic, microscopic and interferometric pictures. Now a day’s commercial world is also using these cameras for making instant prints.