Merrifield's plate of spheres: an outline sphere with a line drawn through its highlight to its darkest band, and shaded spheres showing the full turn from light to dark with their cast shadows.

Concept · Seeing Light

The Light and Shadow Sequence

On a round form under one light, values come in a set order: highlight, light, halftone, core shadow, reflected light, and the cast shadow on the ground.

Surfaces facing the light get the most; the rest turn away and get less. Some drawing courses call this light logic.

  • The order holds on an apple, a head or a fold of cloth.
  • Merrifield noted that a line through the highlight and the center of a sphere crosses the middle of its darkest band.
Halftone
the grays between full light and shadow, where the surface begins to turn away.
Terminator
the line on a form where light gives way to shadow; also called the shadow edge.

See

Image: Internet Archive · Public domain (published before 1931)

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