Fill Light is the light used to supplement the key light. It is used to reduce the contrast in your lighting depending on how much is used. There are different places you can place the fill and that will result in different moods and tones. One of the challenges I’ve had in my personal project is using the fill light effectively. Having too much and your image can be flat. Having too little and your project feels too moody and like a film noir.
Controlling the Fill Light:
The challenge with adding fill light is controlling it. One of best ways to control fill light is with flags and bounce boards.
The white flag (silk) helps to diffuse the light. The red and green flags or more like scrims which takes down the intensity of the light. The black flag completely blocks the light. With the bounce, you can add more light by bouncing other lights like your key or the sun into your subject. There is also the concept of negative fill. When there is just too much light to control and you don’t have enough high power lights to offset the sun, you can use negative fill. Negative fill is the technique of taking away light with the use of flags and large black boards, sheets, etc.
