What is the primary purpose of the key light in a video setup?

The primary purpose of the key light in a video setup is to provide the essential illumination for the subject. It serves as the main source of light that illuminates the subject and sets the overall mood for the scene. The key light is strategically positioned to ensure that the subject is well-lit, allowing for details and features to be visible. This foundational lighting helps to define the subject, allowing filmmakers to control how the audience perceives the scene.

While creating shadows, enhancing color balance, and separating the subject from the background can all be achieved through lighting techniques, these activities are often secondary effects or resulted from the manipulation of various light sources. The consistent and primary role of the key light stands out as the backbone of effective scene lighting, making it crucial in achieving the desired visual narrative in video production.