A camera is the instrument that will give us picture of a person or a scene called a photograph that can be kept for sweet memory. It has become one of the most important means of communication and expression in modern times. Basically, a camera is a dark box fitted with a lens on one side. Just behind the lens there is an aperture which controls the amount of light admitted. A shutter exposes the film to the light for a short interval. A photosensitive film is mounted on the opposite side of the lens. This film has a layer of silver bromide coated on it.
The object, whose photograph is to be taken, is focused on the film. This is done with the help of another lens called a view–finder. On opening the shutter the light from the object enters the box through the lens. An inverted image of the object is recorded on the photo film.
The exposed film is taken out of the camera and developed by a chemical process. For developing the film a solution of quinol and metal is used. During this process the portion on which more light has fallen becomes darker and the image of the object appears in reverse tones. The developed film is put in the hypo solution for fixing the image. That is how the negative of the object is obtained. In the negative white portions appear dark and black portions appear white.
Now with the help of an enlarger, a print or positive is made from the negative. The light coming through the negative is focused on the photosensitive bromide paper. This paper, after developing and fixing, takes the shape of a positive. That is how we get the photograph of an object.
There are a lot of developments taking place in the field of photography. Nowadays, the techniques of making coloured photographs are being used on a large scale. Instant cameras take photographs in a few seconds. These instant cameras are called Polaroid cameras. Some special cameras produce motion pictures like TV and video cameras, the pictures are made electrically. Holography has given birth to three dimensional photography in which we can see the length, breadth and thickness of the object.