Filming & Production
Hard light
Also called: harsh light
Shadow edge is set by the apparent size of the source. A bare bulb, a phone torch or midday sun is small in the frame's terms, so the transition from light to dark happens across a few millimetres of skin. Put a large diffuser close to the subject and the same lamp turns soft.
Hard light is a choice rather than a fault. It carves texture, suits drama and product edges, and it is unforgiving on faces. Distance matters as much as size, because a big source moved far enough away behaves like a small one.