I remember the first book I read about studio light — it was a very old one, wrote in 80th or 90th and it claimed that there are 4 lights to every studio photo: painting light, filling light, contra and light for hair (this last one clearly indicates it was 80th :)) ). The book saw contra as a chance to make your picture more 3-dimensional. In fact it’s how contra light often used in cinematography — that light line on one side of the actor’s figure in large frames.
As I often go for more creative effect, I sometimes use contra as painting light or even sole light in the frame. I also use contra to “fill” mist or smoke that otherwise would look too thin. Let’s look at the examples.
Here you can see how the light from up and behind locally softens colors and contrasts. It also makes skin look even and glowing which is this light’s favorite property for many of my clients.
Here we have natural light from the window as contra (you can also use a big soft-box) and small warm studio light (on pilot, no flash) in front of the model
Here we have one studio reflector 3 o’clock for the model and a soft box in front of the model.