Hard and soft light

The hardness or softness of light depends mostly on three features of the source: the size of its surface, its distance from the object, and the thickness of its diffusion material.

By diffusing hard shadows, softening dark areas, and removing sharp edges, soft light produces more flattering images of the human form.

[1] Hard light comes from a single, usually bright, source, which is relatively small compared to the subject.

Focusing a Fresnel lens makes the rays of emitted light more parallel.

For a point light source, with a tiny area, intensity is inversely proportional to distance.

Certain lensed lighting instruments (such as ellipsoidal reflector spotlights) have a good deal of "throw" and do not lose much intensity as distance increases.

In "hard" light sources, the parallelism of the rays is an important factor in determining shadow behaviour.