Three point lighting is one of the most important, and versatile, portrait lighting setups you can use. Mastering the three-light unlocks an infinite amount of lighting possibilities. This technique can be used in photography, video, and even stage theatre lighting. No matter what the application, the principles remain the same.
1. Key Light
Your key light, or sometimes called the main light, drives the show. It should be the most powerful light in your scene. It will be the one responsible for most of your base exposure and setting the tone for the rest of the lights. Whenever you start designing a lighting setup, forget all the other lights and focus on getting your key right. Once this is right, you can move on to the next light.
In the video, you'll notice that my Key light is not pointed directly at me but across my face. This serves two purposes: it direct the beam of light into the reflector (see below), and it illuminates my face with the "edge light," or the part of the beam of light that is softest and most pleasing.
2. Fill Light
I once heard that "a fill light is a light you never notice until it's gone". It should be subtle, and as the name suggests, fill in the shadows in your scene without overpowering the key light. Many times, dark dramatic scenes even have fill light to keep key parts of the image from falling completely into darkness. Whether you have the slightest amount from a dramatic interrogation table to full brightness clam-shell beauty light, the fill is very important and needs to play nice with your key.
3. Background Light
The background light has one purpose: to separate your subject from the background. The first way to do this is to have a light behind your subject, directed back at them. This style is also sometimes referred to as a hair light, rim light, back light, or kicker. When used like this it should subtly highlight the contours of your subject and still be less powerful than your key light. The second way to separate your subject from the background is to add dimension by lighting the background itself. The light, usually from behind your subject, shines at the background.
Note that as my background light in this video, I actually have three lights instead of one. You can do this just as easily with one light. The difference is that more lights will give you an even spread, while one light will create a spotlight effect. The farther you can place lights away from the background, the more even the spread. Since I have a small room to work with and don't want a spotlight effect, additional background lights were added.
Want a double super bonus? Add in a fourth light and do both! But when you need simple and efficient, three lights do just fine, and either method will do.
When you are building a lighting design, do one at a time. You want to make sure each light does what you want before you add a new one to the mix. Throw out three lights and when you have a problem, before you can fix it, you have to figure out what light is causing the problem. Building one at a time means you can quickly identify and solve any problems you run into.
Light can be anything. It can be an expensive strobe unit or a inexpensive speedlite. It can be professional LED panels or the lamp from your living room. It can even be natural light using the sun and a reflector. As long as you understand the principles, you're well on your way to being a lighting pro.