Three-point lighting, drawn on a real floor plan
Three-point lighting is a key light that shapes the face, a fill that controls how dark the shadow side goes, and a back light that separates the subject from the background. Most diagrams draw it as three arrows round a dot. That shows the idea and none of the decisions: how far away each light stands, how high, how much softer, how much dimmer. This is the same setup on a floor plan, to scale.
- Subjectat 3.0, 2.2 m
- A camat 3.4, 4.2 mEyeline just off the lens
- Keyat 1.5, 3.3 m45°5600KThrough a 90cm softbox
- Fillat 4.7, 3.3 m100°30%4x4 bounce, a third of the key
- Rimat 4.3, 0.9 m25°5600K60%Spotted, flagged off the lens
The key: where the face gets its shape
The key goes roughly 45 degrees off the line between camera and subject, or a little wider where the room allows (it is nearer 60 in the plan above), and above eye level, so its shadow falls down and across the face the way daylight from a window would. Higher and the eyes go into shadow; lower and it starts to look like a torch held under the chin.
The side matters more than most diagrams admit. Put the key on the side of the face turned away from camera (short side) and the near cheek falls into shadow, which gives a face depth and is the usual choice for drama and interviews. Put it on the side turned towards camera (broad side) and the face reads flatter and wider, which suits a brighter, more open look.
The fill: how dark the shadows go
The fill sits on the other side of the camera, lower and softer than the key, and its only job is to decide how much detail survives in the shadow. It is often not a light at all: a bounce board catching the key does it for free. What you are setting is the ratio between the lit side and the shadow side.
| Key : fill | Difference | Looks like |
|---|---|---|
| 2:1 | 1 stop | Bright and even. Corporate, beauty, comedy. |
| 4:1 | 2 stops | Shaped but friendly. Most interviews. |
| 8:1 | 3 stops | Moody. The shadow side starts to go. |
| No fill | Whatever the room gives | Hard drama, night interiors. |
Distance does a lot of the work. Light falls off with the square of the distance, so moving a lamp from one metre to two leaves a quarter of the light on the face: two stops, without touching a dimmer.
The back light: off the background
The back light, or rim, goes behind the subject on the side opposite the key, high, and aimed at the back of the head and shoulders. It draws a thin edge that lifts dark hair off a dark background. It usually wants to be harder and narrower than the key, and it needs a flag on the camera side, because a back light pointing towards the lens is a flare waiting to happen. Too strong and it looks like a halo; it should be noticed only when it is switched off.
Drawing it so a gaffer can read it
A plan that the crew can rig from has a few things a sketch leaves out:
- The room, to scale. Whether the key fits at 45 degrees depends on where the wall is.
- Camera and lens. A 50mm and an 85mm put the camera in different places, and the lights have to stay out of both frames.
- The fixture and what is on it.“Key” does not tell anyone what to take off the truck; “300 watt LED through a 90 cm softbox” does.
- Height and direction, and where the beam lands.
- Intent in a few words: “a third of the key”, “flagged off the lens”.
When three-point is the wrong answer
Three-point is a starting shape, not a rule. A scene by a window wants the window to be the key and everything else to support that story. A night exterior might have one hard source and nothing filling it. Plenty of good interviews are a big soft key and a dark room. Learn it so you know what you are leaving out.
The same setup grows into the full interview lighting diagram, with a background light added. For a studio portrait with two rims, see the portrait diagram, and to draw your own, the free lighting diagram tool needs no account.