Portrait lighting tips: Key lighting and fill lighting photo techniques

Portrait shot with key light and fill light

Key lighting and fill lighting are are two of the most fundamental concepts in studio studio photography. Using both together is a reliable lighting technique not just for portraits, but for many different subjects. Here we’ll look at how a simple setup, combining a key light and a fill light, can lead to great portraits in the studio, and all kinds of other scenarios.

Using a key light and fill light

The mission: Control two lights in a classic key and fill setup

Time: One hour

Skill level: Intermediate

Kit needed: Two light sources on stands (ideally LEDs or flash heads), light meter (optional)

Here we’ll look at how this simple setup of using key and fill lighting can lead to great portraits in the studio, and all kinds of other scenarios.

Read more: The best lighting kits for home studio or location photography

In essence a key and fill are two light sources – one slightly stronger than the other. The key light is the main light used to illuminate our subject, while the fill light provides a lift to the shadows. It’s such an effective technique for lighting because it gives depth and form to our subject. It provides a play of light and shade across them and it’s this that creates a sense of depth and shape to the face. 

But before you get going, you have to set up the lighting…

Indoor studio lighting

1.  Build the lighting

When setting up for key and fill it can be helpful to turn each light on in turn and slowly perfect them, one at a time. This takes some of the guesswork out of lighting when you begin to use two or more lights. Begin by placing the lights in an 8 o’clock and 5 o’clock position.

2. Control the key light

Turn on the key light and take a test shot. At this point, the fill light is turned off. Note how the directional light gives the face a three-dimensional quality but at the moment the shadows on the other cheek are far too deep and the contrast too much.

3. Control the fill light

Now turn off the key, and turn on the fill. Ensure the exposure is locked, then take another test shot. The aim is an underexposed portrait like so. The shadows cast by the nose show that the fill light is straighter than the key, giving the lighting a flatter look.

4. Combine key and fill lights

Next, we turn on both the key and fill lights, then meter and take a shot. The fill light lifts the deep shadows and gives us even lighting. The ratio between key and fill is fairly even, so the contrast is subtle. But we could power down the fill for greater contrast.

Outdoor lighting

Outdoor filling techniques

 Natural light can be used either as a key or a fill in outdoor flash-lit portraits…

1 Get your images
When you’re shooting outdoors with a Speedlight it’s possible to use the sun as a key light and the flash as a fill, or vice-versa. Just like before, we begin here by metering for the key light while leaving the fill off, resulting in a rather high-contrast sun-lit portrait.

2 Position the Speedlight
Next we turn on the Speedlight and position it opposite the angle of the sunlight in order to fill in the shadows and reduce the strong contrast over the subjects face. The flash is in Manual at 1/2 power and fired through a diffusion panel from a 5-in-1 reflector to soften the light.

3 Lift the shadows
The Speedlight fills in the shadows and reduces the contrast. The burst of flash also has another benefit here – it provides a nice catchlight in the subjects eyes. Finally, we could increase the power of the Speedlight so it overpowers the sun, then the sun would be the fill instead.

How much fill light? Lighting ratios explained

Varying the amounts of fill lighting

Varying the amounts of fill lighting

In each of our three portraits above the key light is metered at f/8, while the fill has been varied by reducing the power setting by 1.0 in each – one stop. 

On the left the fill is at f/5.6, which is one stop below the key. This gives us a 2:1 ratio, as the key is double the strength of the fill. In the middle pose the fill is at f/4, giving a 4:1 ratio – this time the key is 4 (or 2) times stronger than the fill. 

On the right the fill is three stops below the key at f/2.8, giving us a ratio of 8:1 as the key is 2 times stronger than the fill. 

But which is right? It’s down to preference. A 2:1 setup is quite flat – fine for high key or beauty shots, but a 4:1 ratio results in more depth. An 8:1 ratio is perhaps too much for our subject, but might work better on another model or scene.

Read more:
Cheat sheet: Simple lighting techniques
The best lighting kits for home studio or location photography
The best LED light panels in 2019