Rembrandt Lighting
A portrait pattern in which a small triangle of light appears on the shadowed cheek, below the eye.
In depth
The triangle appears when the key is roughly 45° to the side and 45° above, so the nose shadow reaches down to meet the cheek shadow but leaves a lit patch between them. It should be no wider than the eye and no longer than the nose. The pattern is dramatic and sculptural, and it suits strong bone structure.
Examples in practice
Raising the key until a small illuminated triangle appears under the shadow-side eye marks the classic Rembrandt position.