Video starts with a camera, as all picture taking does. In still and motion-picture film photography, there is a mechanical system that controls the amount of light falling on a strip of film. Light is then converted into a pattern of varying chemical densities on the film. As a physical medium, film can be cut, spliced, edited, and manipulated in other ways, as well.
In electronic photography, the light from an object goes through a lens, as it does in film photography. On the other side of the video camera lens, however, light is converted to an image by an electronic process as opposed to a mechanical or chemical process. The medium for this conversion has changed over the years. It began with tube cameras ...