Practical

A light that appears in the frame and lights it too: a lamp, a window, a candle. Motivation and source in one.

A practical is a light that acts in the fiction and works on the crew's side at once: the lamp, the candle, the neon sign, visible in frame, actually illuminating, explaining the light the audience sees. Source and motivation collapse into one honest object.

Motivation and source in one is why cinematographers build scenes around practicals: light with a visible reason reads as world, not technique, even when hidden units quietly do the heavy lifting, keyed to the practical's story. The principle travels: on a page, a glow should come from something, our gold reads as lamplight because the design gives it a source.