A camera is a fairly simple piece of equipment in its basic structure. One must not be put off by the numerous levers, buttons, scales and other gadgets on the outside. These are all extremely useful aids but are not completely essential.

The essential part of the machine is what gives it its name; the camera obscura. This is Latin for dark room. Photographs are produced when rays of light penetrate into this dark chamber. The light must enter through a small opening and strike against a sensitive film. The surface of the film is covered in an emulsion of chemicals which capture the images being carried by the light rays. The small opening, or aperture, must have a mechanism to cover it to stop light from entering all the time. The mechanism must also be able to open the aperture to let the light in. This mechanism is called the shutter. In a simple camera this is about the only moving part.

In more expensive cameras the fittings include mechanisms which can vary the exposure time which determines how long the shutter will stay open. This can range from a thousandth of a second for fast-moving subjects to one second or more for still dimly-lit scenes. Other controls include an aperture selector to vary the amount of light passing through the lens, and a focusing mechanism to produce a sharp image.

The camera obscura has long been known to man and Leonardo da Vinci made accurate drawings of it in the fifteenth century. It was not until 1839, however, that the first commercially available cameras were made in Paris by Alphonse Giroux for Daguerre.