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This post was most recently updated on November 13th, 2022

Adding a layer of atmosphere to a shot is essential for photographers. Knowing the purpose of a key light helps the understanding of lighting setups.

What Is A Key Light?

A key light is the first and primary light source for your shot. It is the prominent light that shines on your subject so is either directly in front or angled for a specific effect.

As a foundation, your key light will go a long way to determining the lighting design. The color, angle, and strength of the key light can set the overall mood and atmosphere of your shot. A key light is often focused on the main subject to determine how you want them to be highlighted.

A key light can be involved in a setup of multiple sources of artificial light. In this case, a key key will be the light source with the biggest effect on the subject. Whether a camera mounted flash, a stage light or a mere lamp, the key light is the one that acts as the primary source of light.

For an outside shot, even the sun could be classed as a key light. When shooting indoors you could count a candle or the fire as your key light if they are bright enough.

What Is The Purpose Of A Key Light?

The main purpose of a key light is to set the core tone then illuminate the main subject in a shot. A key light acts as an anchor to the lighting scene yet also works to help feature the dimension and specific form of a subject. Its positioning is integral and brings some focus to the shot.

For that reason alone the key light is often directly in front of the subject of your shot.

The key light can properly highlight the dimensions and forms of a subject that you want an audience to focus on. As the primary light source, how a photographer uses a key light can determine the look of a shot. You could want the shot to look moody and mysterious or light and cheery, the key light would control that.

Intended use of a key light can also be to illuminate an important, specific part of your subject. Perhaps to lend focus to a facial expression or an object in a shot you want to draw attention to. For that, the key light can be at an angle instead of directly facing the subject.

The intention remains that you wish to use the key light to highlight an aspect of the shot. How a photographer uses a key light defines the overall mood of the shot and elevates it.

Using a key light properly is a skill any photographer should learn. Excellent use of a key light can propel your shot from ordinary to interesting and dramatic.

How Do You Use A Key Light?

How Do You Use A Key Light

Photographers can use a key light in several different ways. With only a slight adjustment of the key light, several different effects can be created and initiated. Whatever a photographer wants to bring out from a shot will usually involve the key light.

Using Angles

The use of angles is important on a shot. To use angles with a key light, position it on a light stand relative to the subject. This can draw focus to a certain facial feature, an expression or an object.

Shadows can also be created using a key light. If desired in a three-point lighting setup, the key light would be set at a 30 to 60-degree horizontal angle from the camera. With the left side lit, the left side would be shaded and create a prominent shadow across the subject’s face.

Subversive Effects

A key light can even be used to create a subversive effect. There is an assumption that the more common vertical position for a key light is at a 30-degree angle to be just above the eye line. Placing the key light higher or lower would produce a range of interesting effects.

If higher, the key light tends to highlight cheekbones which may be a feature of your subject you want to focus on.

Another subversive effect involves natural or ambient light. This is expected to be overhead but when positioned low it can help distort the features of the subject. Great for shoots where you want to create weird and wonderful effects.

Indirectly

A key light can also be used indirectly. You could make use of obstacles such as a street lamp, a tree or a window to merely highlight a subject’s location. This would make your subject stand out in a shot and bring some focus without directly illuminating them.

Creating an interesting shot could also mean changing the color of your key light. With a specific choice of colored backlights you could bring some more depth to a shoot.

The key light can be used on its own to create a shot of high-contrast. This works especially well without any other lights being used to help illuminate the background.

What Types Of Key Lighting Are There?

The type of key lighting used largely depends on what mood or atmosphere you want to create. Essentially, there are two types of key lighting.

High Key Lighting

Using white and light tones, high key lighting aims for minimal shadows and contrast. By limiting the lighting ratio you can create a brighter composition for a cheerful and upbeat mood with more highlights.

It can be achieved by using three-point lighting of a key light, fill light and a backlight for a uniform lighting pattern.

Low Key Lighting

This type of key lighting is defined by its use of darker tones including shadows and high contrast. There is a harsh transition between shadows and highlights. Deep blacks are prominent and shadows are usually controlled by a reflector or fill light.

Used well, the shadow can highlight certain contours on a subject. In effect, the subject would appear isolated which would allow the audience to focus on their features. Low key lighting is especially important on shoots where you want to heighten negative emotion.

This could be to create an element of tension with some mystery and drama thrown in.

Soft And Hard Key Light

Photographers can also use a soft and a hard key light to accentuate the look and mood they want. A soft key light is diffused and used for a balanced shot. To create a shot with intricate shadows and deep colours, use a hard, focused key light.

Final Thoughts

A key light is crucial to a lighting setup. It brings in a foundation for the shot as well as lending a focus to a subject. The key light is the basis and starting point for a shot’s lighting scene and a marker for where other lights should be positioned.

Once the key light is set, the rest of the lighting scene can follow to create and build a mood. That could be the position of other lights such as back lights or fill lights. Use high and low key lighting to control your use of shadows and color.

Learning the purpose of a key light goes a long way to appreciating how you can create a mood for your shot.