Film and Exposure
Any discussion of lighting must consider the medium that collects the light. All cameras imitate the human eye, incorporating the light-gathering lens and the regulating iris. The eye forms its image on the light-sensitive retina, which is analogous to photographic film and the video target.
Film consists of a clear plastic base (usually cellulose triacetate or polyester) coated on one side with a photographic emulsion. The emulsion is made up of light-sensitive silver halide crystals suspended in a thin layer of gelatin. A top coat protects the emulsion from scratches (see ...