Three-point lighting: how to light an interview

The difference between a video that looks professional and one that looks improvised is almost never the camera: it is the light. Three-point lighting is the foundation used for interviews, corporate portraits and testimonials, and it takes five minutes to understand.

The three lights

• Key light. The dominant source, the one that defines the shape of the face and where the light appears to come from. Place it about 45 degrees off the camera axis and slightly above eye level.
• Fill light. Goes on the opposite side of the key and softens the shadow it leaves. It must not cast a shadow of its own: its job is to lower contrast, not to compete.
• Back light (or rim light). Sits behind the subject, aimed at the shoulders and the back of the head. It draws an edge of light that separates the person from the background. It does the most to make an image look produced, and it is the one most often forgotten.

How much difference between key and fill

That ratio defines the character of the image. If the fill is half the intensity of the key, the result is soft and friendly: the norm in corporate communication. At a quarter or less, you get defined shadows and a dramatic tone, useful for a documentary or a hard-hitting testimonial. With both lights equal the face flattens and loses volume.

Diffusion and colour temperature

A small, direct source produces hard-edged shadows; the same source behind a diffuser, or bounced off a white surface, produces soft ones. The rule is simple: the larger the source relative to the face, the softer the light. That is why a large panel placed close flatters more than a powerful lamp far away.

And a warning that ruins many shoots: do not mix colour temperatures by accident. If one light is daylight (around 5600 K) and another is tungsten (around 3200 K), one side of the face comes out blue and the other orange, and that cannot be fully fixed in post. Pick one temperature and bring every source — the window included — to that same reference with gels or settings.

The fourth light: the background

The scheme is called three-point, but in practice there is almost always a fourth source lighting the background or a detail of the set. It adds depth and avoids the cheapest-looking setup there is: a well-lit person in front of a flat grey wall.

It works with natural light too

You do not need gear. A large window makes a perfect key light if the person sits at an angle to it; a white card or a pale wall on the other side acts as fill; and the back light can be solved by finding a position where some light comes in from behind. What does not work is seating someone with their back to the window: the camera exposes for the background and the face goes dark.

Common mistakes

• Lighting head-on from the camera. It erases every shadow and with them the volume of the face.
• Two lights of similar intensity at opposite angles. Creates two crossed shadows and gives the artificial lighting away.
• A background brighter than the person. The eye always goes to the brightest area of the frame.
• Lights at floor level pointing up. Gives you the horror-story flashlight effect.

One last thing: three points is not an obligation. In many portraits a single large, well-placed source with a bounce card looks better than three badly balanced lights.