Zoetrope

Repeated figures stand around the frame, each one a step further through the same movement. Pass them in order and a single motion appears out of the repetition.

The device is older than film. William George Horner built the spinning drum version in 1834, and the principle it demonstrates is the one every moving picture still runs on.

Each copy holds one position from one movement, in order, spaced evenly. Copy one has the arm down, copy two has it a little higher, and so on around the frame.

The copies have to be identical in everything except the pose. Same person, same clothing, same light. Any other difference between them reads as a crowd rather than as one body in time.

Movement comes from something passing them. A camera travelling along the row, or a shutter, or a strobe. Static copies with a static camera give you a frieze.

Use it for a title sequence, for a dance piece, and for anything where the mechanics of animation are part of the subject.

Skip it when the movement is complicated. Ten copies can only hold ten positions, so a subtle action loses everything between the steps.

Stop motion moves one object a little at a time and photographs each position as a separate frame, so the audience sees one object moving. A zoetrope puts every position in the frame at once and lets the eye assemble the motion.

The test is how many copies are visible. One object at a time is stop motion. Every step present together is a zoetrope.

Identical copies come back in the same pose, which is a pattern rather than a movement. Say each copy is one step further through the action, as the note asks.

The second failure is a smooth animated figure, because a model will resolve the sequence into ordinary motion. Say the figures are discrete and separate, and that the movement comes from the repetition.