Time Lapse and Stop Motion
The principle of fast motion can be extended to the point where the camera exposes one frame every second, every minute or even every hour. This technique of so-called time lapse photography is useful for depicting processes which are normally far too slow to be observed live: the growth of plants, changes of weather in the sky, etc.
For time lapse films the camera operates at the single frame speed, with an automatic unit which exposes a frame at pre-set intervals. For growth studies the plant is usually set up in front of the camera in normal daylight. Immediately before every exposure the timing mechanism obscures the prevailing daylight, switches on lamps (to ensure uniform exposure for every frame). It then switches off the lamps and readmits the daylight after the exposure.
Stop motion involves stopping the camera during the run of a scene, making a change of some kind in the scene and then continuing filming. The effect is one of a sudden change. One can therefore make something or someone appear or disappear in an instant in accordance with the best tradition of magic.
Related to these techniques is the art of animation. Here inanimate objects are moved by the cameraman, a little at a time, between exposures. The objects may be three-dimensional as with puppets, or two-dimensional as with flat diagrams or drawn cartoons.
Cartoons were traditionally made by photographing a long series of drawings each of which has been drawn slightly different from the one preceding.
The changes represent the progressive movement of the portion of the drawing to be animated, such as a cartoon character. To reduce the amount of labor involved in the drawing, a detailed background is usually drawn on a sheet of paper while the animated objects in the foreground are drawn on sheets of transparent plastic (cells).