9

What is lighting ratio and how is it calculated?

mattdm
  • 143,140
  • 52
  • 417
  • 741
Canon Gangsta
  • 3,470
  • 5
  • 30
  • 35

1 Answers1

14

It's the difference between your main light and fill light expressed as a ratio of brightness. Example: if your main light is twice as bright as your fill light, the ratio is 2:1. A high ratio will give a more contrasty effect, as shadows cast by the main light will still be dark. A lower ratio means the fill light lessens the effect of shadows cast by the main light, giving a flatter effect.

Note a difference of one f-stop is a factor of two, so a ratio of 2:1. Similarly, two stops is 4:1, and three is 8:1.