Abstract: Lighting is an essential component of visually rich cinematographic images. However, the common computer graphics light source models, such as a cone-shaped spotlight, are not versatile enough for cinematographic-quality lighting. In this paper we describe the controls and features of a light source model for lighting computer graphics films. The model is based on generalized light cones, emphasizing independent control over the shape and texture of lights and shadows. While inspired by techniques of real-world cinematography, it is tailored to the needs and capabilities of computer graphics. The model has been used successfully in production over the past few years, to light many short works and the movie Toy Story.