Lighting reference for artists: the five setups to know (Rembrandt, loop, split, butterfly, rim), how to read light on a photo, and a 15-minute value drill.
Lighting reference is a photo where you can name where the light comes from and see how it wraps around the form. Artists use it to learn five studio setups (Rembrandt, loop, split, butterfly and rim) and the four zones of light on any surface, so a drawing reads as solid instead of flat.
A good lighting reference photo has one clear main light, a direction you can describe in one word (left, right, above, behind), and shadows with clean edges you can trace. Mixed light from windows, lamps and a flash blurs those shapes, so a deliberately lit studio photo teaches the logic of light much faster than a random snapshot.
Photographers call that main light the key light: its job is to show the form and dimension of the subject, and it can be hard (focused) or soft (diffused) ( Wikipedia: Key light ). Learn to find the key first in every reference.
Five lighting setups cover most portrait and figure reference: Rembrandt, loop, split, butterfly and rim light. Each one is defined by where the key light sits relative to the face, so once you can name the setup on a photo you also know where the shadows must fall when you draw the same head from imagination.
Rembrandt: key light high and to one side, leaving a small lit triangle under the eye on the shadow side. The triangle should be no longer than the nose and no wider than the eye, and the fill is set to about half the power of the key ( Wikipedia: Rembrandt lighting ).
Loop: a softer, more frontal version of Rembrandt. The nose shadow loops down toward the corner of the mouth.
Split: light from 90° to the side, splitting the face into a lit half and a shadow half. High drama, strong character.
Butterfly: light high and directly in front, leaving a small shadow under the nose. Common in beauty lighting.
Rim / backlight: light from behind gives the subject a rim of light that separates it from the background and highlights contours ( Wikipedia: Three-point lighting ).
Read light on a reference photo by finding four zones on every form: the highlight (the brightest point), the halftone (the surface turning away), the core shadow (the darkest band where the form turns fully away) and reflected light (bounce inside the shadow). Beginners most often skip the core shadow, which is why their rendering looks flat.
Painters have used this contrast of light and dark to model volume for centuries; the technical term is chiaroscuro, Italian for "light-dark" ( Wikipedia: Chiaroscuro ).
Published 2026-06-02 on the Refimages blog.