Traditional Culture Encyclopedia - Photography major - How to calculate the light ratio of portrait photography?

How to calculate the light ratio of portrait photography?

The same distance, the same accessories, the same power, adjust the output power, for example,11-1/2 differs by an aperture, which is the light ratio of 2: 1.

Public intermediate key

Main lamp 1/4 output, auxiliary lamp 1/8 output, contour lamp 1/2 output.