Feathering the light is using the shadow edge of your light to control your shadows.
Most beginning photographers seem to start out in the studio with their light pointed directly at their subject. And this works in many situations. You can keep doing that and all will be well. But if you want to take things up a notch and gain more control over the light on your scene you will need to learn how to position the light to control its coverage. And that’s what we are here for today. Control the stamp of light on your subject be feathering the light.
The first thing to learn about feathering your light is that it does NOT make your light softer. We know that the larger the light source as seen by the subject the softer the light. What happens when you feather the light? Take a look at the images on the right where we are looking over the model’s shoulder at the light. On the top the light is pointing directly at the subject. On the bottom the light has been pivoted towards the camera to point more across the face of the subject. In doing so the light has become narrower, which is smaller. If you think back to the post about shadows you will see this is more like a strip light where the shadow edge quality will be the same up and down (the long dimension of the softbox is still the same size), but the shadows from right to left across the face (the nose shadow) will be harder because the width of the light is narrower.
The light across the face is slightly harder, but it is more even. The coverage is wider. But it isn’t any softer.
We can also feather the light away from the camera, towards the background. This will make the light across the face narrower and harder with deeper shadows. It is more akin to a split light when you do this. Let’s look at examples.
Here I am using a hard light source to emphasize the shadow edges. On the left the light is pointed directly at the subject. In the middle the light has been pivoted towards the camera to cover a wider area of the face, opening up some of the shadows while at the same time making the shadow edge harder and more defined. Over on the right side I pivoted the light towards the background for another look that is even more shadowed and contrasty. Again notice that the nose shadow to the side has become very hard edged due to the light becoming much narrower.
Feathering becomes an even more powerful tool when working with multiple subjects in the photo. Here I have two subjects and a hard light.
Again, with the light pointed directly at the pair there is a strong falloff in light from left to right with deep shadows on both faces. By pivoting the light towards the camera the light evens out between the two faces as seen in the middle. Pivoting towards the background makes the difference in exposure between the subjects even farther apart.
Now let’s look at it with a softer light, this time a 2x3-foot softbox.
This time I changed the order and you will see why in a moment. I started out the same with the softbox pointed directly at the subjects. Turning it towards the background exacerbated the problem of uneven exposure on the two subjects. Feathering the light towards the camera for the third image evened out the exposure. And in the bonus image I turned the light even more towards the camera and you can see that this lit up the subject farther from the light more than the subject closer to the light.
Here is a diagram to help explain.
There is your control via feathering.