key lighting setup
Production & Filmmaking
December 15, 2021

A Beginner’s Guide to Key Lighting: What It Is and How to Use It in Your Lighting Setups

By Daniela Bowker 10 min read

Highlights

  • The key light is the main light in your setup
  • You can use a key light alone or combined with one or more other lights - but it's always the main one
  • A key light can be any type of light, from a softbox to a ring light

When you start learning about artificial light, it can feel incredibly daunting. There are different types of light, which can be used in different lighting setups. They have different temperatures and can be modified in countless ways. Lighting can be as intricate and complicated as you can dream it to be. But when you break it down to its components, lighting doesn't have to be overwhelming. So let's begin at the beginning: what's your key light, and how do you use it?

What is the key light?

The key light is the main light in your setup. It's key to the scene if you like. Your key light is the foundation upon which your entire lighting design is based: it illuminates your main subject, sets the tone for the scene and gives it shape. It doesn't matter if you are constructing a YouTube lighting setup or a scene from a blockbuster movie: every light is added on and built around the key light.

A key light can be almost any type of light: it can be a softbox or the sun. You could use a candle or a Fresnel light. Whatever the source, if it's the main one, it's the key light. They can be set at varying angles. Light modifiers can be used with key lights, and you can color them however you wish. Key lighting can be hard or soft. You might want a high key or a low key lighting setup. If your scene involves movement, your key lighting might have to move with it. Whatever you use, however you use it, your main light is your key light. 

What's the difference between key light and fill light?

While you can use just one light in a video, you will often find that your key light creates shadows that need lifting. The light you use for this is your fill light: it literally fills in the shadows. When it comes to key light vs. fill light, your fill light will be less intense than your key light, maybe by about 50%. The fill light is there as a supporting act for the key light; it isn't the star of the show. 

The fill light is often situated at the same angle from the camera as the key light but on the opposite side. So if the key light position is 45º camera right, the fill light is 45º camera left. But it isn't always the case. Most importantly, you place your fill light to complement the light from your key light. And it doesn't have to be a light, either. For example, a fill light can come from a reflector or bounce card.

The main light is coming from camera left. Can you see how the right side of the frame has slightly deeper shadows?

4 ways to use a key light in different lighting setups

Given that your key light is your main light and will feature in every lighting setup you create, there are as many ways of using one as you can imagine. Here are a few examples of how you can use a key light for video.

3-point lighting

When you start using multiple lights in a scene, the 3-point lighting setup is one of the first that you will learn.

It uses 3 lights: a key light, a fill light and a backlight (sometimes called a hair light or a rim light). The key light provides the primary illumination. While you can vary the positions in a 3-point setup enormously, a good starting point would be to place the key light at 45 degrees camera-left or camera-right. Next, balance the shadows from the key light with the fill light at 45 degrees camera-right or camera-left, respective to the key light, at about half its intensity. The backlight is there to prevent your subject from looking as if it is floating in space. It brings depth and definition to the scene. The backlight is usually on the same side of the camera as the key light but coming from behind the subject.

Hard vs. soft lighting

Hard vs. soft lighting means light that has defined and definite shadows or light that is diffuse and wraps itself around your subjects. Key lighting can produce either hard or soft light. To do so, you just need to remember 2 related points:

  1. The further away you position your light from your subject, the harder it will be.
  2. The bigger the light source, the softer the light will be, and conversely, the smaller the light source, the harder its edges will be. By moving your light source closer to your subject you make it comparatively larger, and therefore, softer.

To help maintain hard or soft light, you can use modifiers. For example, flags and barn doors can keep light hard by preventing it from spilling into the shadows. Diffusers and honeycombs or grids can help soften the light, giving you gentle shadows.

The soft, diffuse light means barely any shadows.

Notice how defined the shadows, for example, from glasses, are?

High-key and low-key

As different as high-key vs. low-key lighting might look, they both use key lights. For high-key lighting, you want lots of soft, diffuse light coming from broad sources. Both softboxes and umbrellas are good for high-key lighting, but if you're unsure which is best, check out our comparison article about softbox vs. umbrella.

High-key is often filmed in black and white

 

For a low-key scene, you might find that just a key light is sufficient. You don't necessarily want hard light for low-key lighting, but you don't want too much spilling onto your background. This makes modifiers important; you might find grids, barn doors or flags and negative fill useful. Think about angling your key light to create unusual shadows or lighting shapes.

The key light is a fire, keeping the entire scene very dark.

Backlighting 

While a backlight is a standard part of the 3-point lighting setup, backlighting is a lighting technique in its own right. Here, your key light will come from behind your subject, creating a gorgeous halo of light around them. It can work especially well in natural light, with the sun coming from behind your subject, but you can use any light as your key light.

This back light has created a beautiful halo.

Think about your angles

Whatever type of setup you choose, think about your key light's angle. It will make all the difference. For something very moody, try split lighting, with the key light at 90 degrees to the subject. If you want something very bright and airy, use a ring light as your key light, which comes from the same position as your camera. What about lighting your subject from overhead? Whatever your key light, move it about!

That's a wrap

That's your introduction to key lighting. Your key light is your primary light source, and everything else grows from it. It sets the feel and the tone, and it's the one light your scene can't do without. Don't be afraid to experiment with where you position your key light, how you modify it and the colors you apply to it. If you don't like it, you can always change it.

 

About Daniela

Daniela is a writer and editor based in the UK. Since 2010 she has focused on the photography sector. In this time, she has written three books and contributed to many more, served as the editor for two websites, written thousands of articles for numerous publications, both in print and online and runs the Photocritic Photography School.
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