What: Lighting where shadow dominates light at a high ratio to build drama.
Why: A high lighting ratio charges the image with tension and mystery and isolates the subject.
How: Use one side light source and expose for the lit part so the rest sinks into shadow.
Common mistake: Raising exposure to show detail, so the drama is lost.
Exercise: Shoot a portrait with one window light in a dark room, exposing for the face only.