Design Nomenclature / Light & Optics
Area light
Also called softbox, quad light, mesh light, emitter
An emitter with finite extent — rectangle, disc, sphere, or arbitrary mesh — radiating from every point on its surface. Because different parts of it are visible from different points in shadow, it generates penumbrae natively, and its reflection appears as a specular highlight of matching shape.
In practice
The controlling number is angular size from the subject, not physical size. A two-metre softbox across a large room is a hard light.
Not to be confused with
- Point lightAn idealized source of zero extent radiating equally in all directions from a single position. Because it has no size it subtends no solid angle, so it casts geometrically hard shadows with no penumbra whatsoever, and its illuminance obeys the inverse-square law exactly rather than approximately.
- Shadow softnessHow wide a shadow's penumbra is, governed by one quantity: the angular size the source subtends from the point in shadow. A source is hard or soft only relative to a distance — the same softbox is soft at a metre and hard at twenty.