Fill light

The gentler light that opens the key's shadows: not a second opinion, a mercy. Its ratio to the key sets the scene's drama.

Fill exists relative to the key: where the main light carves, fill decides how deep the carving stays. Strong fill flattens toward openness and comedy; faint fill leaves the face divided and serious. The key-to-fill ratio is the lighting plan's emotional dial, spoken in stops.

Fill need not be a lamp: white walls, reflectors and negative fill's absence all do the job, and the subtlest fills are simply the world bouncing back. The judgement is what the shadows are for, our own imagery runs low-fill by conviction, shadow left intact so the single warm source keeps its authority.