(An excerpt from my forthcoming film book, "Making Your First Blockbuster". coming 2019).
Three-point lighting goes back to the 1930s, when Hollywood actors were all lit a certain way. I like to think of it as a foundation, a starting point that you can move on from and tweak. The three main lights in three-point lighting are:
The main light source in the scene. This can be the light from the window, the desk lamp, or if you’re outside, the sun. It can be artificial light or natural light. A good starting position for the key light is at a 45-degree angle between your talent and the camera, and at a 45-degree downward angle. This is commonly known as the 45/45 rule. (“Rule” of course meaning a good starting point.) You set the exposure on the camera by this key light.
Back light, as its name suggests, back lights the actors. Placed behind them, the light creates a rim or halo light around their back, head, or shoulders to bring them out from the background. Picture a person wearing a black suit in a dark room. A back light would define them and show us their form against the darkness.
Fill light “fills” in the shadows caused by the key light. It’s normally placed on the opposite side of the camera to the key light, and is of a lesser intensity than the key light in order for us to see the effects of the key light. If the fill light was the same intensity, you wouldn’t see any shadows at all since the two lights would balance each other out. You set the mood of the shot by this fill light.
Look at this example of Wonder Woman (2017) (Gal Gadot) to see three-point lighting in action. Keyed from the right hand side of the frame, a little fill on the left and very strong back light.
When blocking your action and setting up the shot, keep the camera on the darker fill side of the actor’s face. When the key light illuminates the actor, the light wraps around their face gradually getting darker towards the camera. This look very pleasing as the texture is revealed on the actor or an object. If you shoot on the same side as the key, it might look a little flat as the exposure is even across their face. Take a look at the example below where we see Daniel Craig as James Bond in Spectre (2015). See how the light is brighter on the other side of the face where the key light is? If Craig looked the other side of the camera off to the right, the camera would then immediately be on the key side, not the fill side, and this approach wouldn’t have the desired effect. Notice the highlights in both eyes too.
If you’re filming someone of age or lighting most other actors in a scene, you want to make them look the best they can. Highlighting all their skin imperfections, lines, and blemishes wouldn’t make you a very popular DP.
So when lighting older actors bring the key light around to the front a little more, almost next to the camera. This key light would now be almost all fill light, causing no shadows at all. What this light then does is fill in all the marks and contours of the face, making the older subject look better. This example shows how we start off with the three-point lighting model and adjust it accordingly to suit the film or our subject’s needs.
To ensure this approach, you would need to allow for this in the blocking phase so work with the director, listen to their initial thoughts and then you can suggest some blocking ideas to make this work for lighting too.
Look at this example to the left from James Bond film Casino Royale (2006). The scene is blocked so Bond (Daniel Craig) is shot on the fill side of the light coming from the table lamp keeping him looking moody, and M (Judi Dench) is position more front on so the light fills her face.
SHOOTING ON THE FILL SIDE IN BOTH DIRECTIONS
If the motivated light source is well established on a particular side of your actors, blocking the scene out to shoot on the fill side shouldn’t be a problem. However, sometimes the blocking might mean that both actors are facing in the same direction while they talk, maybe sitting at a bus shelter or in a hospital waiting room. So how can we maintain shooting on the fill side for both reverse angles when we film each of their single shots? Well, it is possible; you just have to be very crafty.
Once you’ve established the key light from one side, you can subtly reverse it to the opposite side of the other actor to maintain the aesthetic on both sides. This can only work if you find yourself in an environment that has a fairly soft even spread of ambient light with no strong sources of identifiable light. The ratio between the key light and fill light must be very low. Maybe it’s a bright pub or bar, a school, or office location. With light all around, the audience won’t notice that the light on the opposite side of each angle is in fact a little brighter. Look at the example above from Wonder Woman (2017) of two cross-cutting reverse angles to see how the key light jumps from one side to the other, allowing us to keep the aesthetic and maintain shooting on the fill side.
"Making Your First Blockbuster" is due to be released early 2019 from Michael Wiese Productions.