Fill Lighting in Photography

What fill light does

A fill light is a secondary light that brightens the shadows created by the main, or key, light. It reduces contrast, helps retain detail in dark areas and can add a small catchlight in the eyes. Fill should support the key rather than compete with it, otherwise the subject can look flat or show two competing sets of shadows.

If you are new to the idea of a key light, see lighting basics for photography.

Fill sources

• Reflectors: white, silver or gold collapsible discs, or white foam board, bounce key light back into the shadows. White is gentle, silver is stronger and more contrasty, gold adds warmth.
• Walls and ceilings: a light-coloured wall near the subject acts as a free reflector.
• A second light: a flash or LED set at lower power than the key.
• Fill flash: a flash used to lift shadows when the main light is the sun or a window.
• Ambient light: in a bright room, the surroundings may provide enough fill by themselves.

Setting the fill level

Fill is usually described by the ratio between key and fill. A 2:1 ratio means the key is one stop brighter than the fill, and 4:1 means two stops. Lower ratios look softer and more open, while higher ratios look more dramatic. There is no correct ratio, but a gentle fill is a reasonable starting point for portraits. For more on this, read contrast lighting in photography.

Step by step

1. Position the key. Place it where you want the main shadows to fall.
2. Check the shadows. Look at how dark they are and decide whether you want more detail there.
3. Add fill from near the camera axis, on the opposite side or low in front, so it fills shadows without making new ones.
4. Start weak. Raise the fill until the shadows hold detail but still show shape.
5. Check the catchlights and the overall mood, and adjust.

Fill flash outdoors

In bright sun, faces can have dark eye sockets and hard shadows. A small amount of flash, set well below the sun’s strength, lifts those shadows while the sun still looks like the main light. This is especially useful with backlit portraits. Many cameras offer flash exposure compensation so you can dial the fill down, for instance by a stop or two, and then adjust by eye. A reflector is a quieter alternative that needs no batteries.

Mistakes to avoid

• Fill as bright as the key, which flattens the face
• A fill placed too far to the side that creates double shadows
• Mismatched colour between the key and fill, such as warm sun with cool LED
• Forgetting that reflectors can make a subject squint if aimed too strongly at the eyes

Using a lightbox

A lightbox for product photos (see product photography lighting) is a form of built-in fill: translucent walls surround the item so light arrives from several sides and shadows stay soft. Place lights on both sides, and add a white card in front if the front looks dark.

Questions

What is fill flash used for?

It lightens shadows on a subject, typically outdoors or in backlit situations, without making the picture look flashed.

How can I improve the lighting in a photo?

Start by moving your subject or yourself, then soften harsh light and add a reflector. Our guide to direct lighting offers more options for managing harsh sun.

For a fill-heavy setup built for headshots, see clamshell lighting.