Light and shadow on form: six zones that make things round

Why does a circle on paper become a ball? Not because of its outline, but because of how light falls across it. When one light source hits a round form, the light always organizes itself in the same order. Learn that order once and you can make anything look solid: an apple, a cup, a cheek.

The six zones

1. Highlight: the small, brightest spot where the light reflects straight to your eye.
2. Halftone: the lit side of the form, getting gradually darker as it turns away from the light.
3. Terminator: the line where the light ends and the shadow begins.
4. Core shadow: the darkest band of the shadow, just beyond the terminator.
5. Reflected light: light bouncing back into the shadow from the table or a nearby wall. It is always darker than any value in the light side; a common beginner mistake is to make it too bright.
6. Cast shadow: the shadow the object throws onto its surroundings, darkest and sharpest right where the object touches the surface.