Ratio Lighting

Ratio Lighting relies on two lights, a key light and a fill light. Each are set at approximately 45 degrees to the model, though you can shift them a bit for creative purpose.

The key light delivers the most light except when using a ratio of 1:1 which is a rather flat and unattractive set up. The idea is to add more light to one side of the face and less light to the other to create a difference in shadow as can be seen in the image to the left. The bigger the difference in the power of the two flashes the darker the fill side will be.

The ratio is worked out by the number of stops between the output of the Key light and the output of the fill light, so:


1:1 Ratio – Same output

2:1 Ratio – 1 stop Difference

4:1 Ratio – 2 stop Difference

8:1 Ratio – 3 stop Difference

FullStop Half Stop
f1 f1.2
f1.4 f1.7
f2 f2.3
f2.8 f3.4
f4 f 4.7
f5.6 f6.7
f8 f9.5
f11 f13
f16 f19
f22 f27
f32 f38
Key Light at f5.6 and Fill light at f5.6 is a 1:1 ratio

Key Light at f5.6 and Fill light at f8 is a 2:1 ratio

Key Light at f4 and Fill light at f8 is a 4:1 ratio

Key Light at f8 and Fill light at f22 is a 8:1 ratio

The ratio is the difference between the meter reading from each light fired on its own.

The basic setup looks like this:


Again all that remained was to take the theory into the studio: