Things to consider when studying light and your subject
1. Brightness- Consider how bright your light source is relative to the overall scene. Remember unless the light source is limited by something it will head in all directions.
2. Lightness- How much of the light is perceived to be reflected from surfaces around the scene.
3. Inverse Square Law- Illuminance is the amount of light that falls onto a surface. As the light is moved further away from the surface, the same light is spread over a larger surface and the illuminance decreases; thus the Inverse Square Law.
Adapted from Fundamentals of Photography by Tom Ang