What Is A “Fill-In” Light?

Note: With the recent articles I published about using one light as a means to get started with the study of lighting, I thought I would re-publish this article of what a second light would do to your images.

What Is “Fill-In” Light?

by William Lulow

In one of the previous blog articles, I wrote about “Building A Lighting Arrangement,” utilizing several lights. Although this is the right way to begin using artificial light, and perhaps the ONLY way to begin, it should be clear that just one light creates a series of shadows in a photograph where no information is visible. That’s also what we get when we use the sun as a primary light source. The natural progression would be to try to add some detail where the shadows create just blacks. This is the basic reason for adding a second light. But how can we do this when we are shooting outside? There are actually a number of ways.

Normally, the second light in a lighting arrangement will add some more information, fill in shadow areas or provide some interesting highlights. More information could take the form of making the background lighter, thereby adding detail to the photograph. It could be added to the foreground, thereby lightening the shadows. Or, it could be added from the sides to create different highlights.

I always begin by adding a second light, or a FILL-IN light in the front to lighten shadow areas a bit. Once you set up your main light, your second light should come from the opposite side of the camera. So, if your main light is high and to camera left, the fill in light should be low and to camera right. The thing that is most important to remember is that the second light should be less intense than the first (main light). If you have two lights of the same intensity, you will wind up with conflicting shadows which give the image an unnatural look. One good way to make sure that the intensity of the second light is less than the main light is to have bulbs of different wattages. If you use a 500watt photoflood for your main light, use a 250watt bulb for your fill in light. Or, if you are using flash, make sure your main light is on full power and your fill in light on half power. (Or some other setting that will yield a properly exposed image).

If you are working outdoors in natural light, I try to put the sun BEHIND my subjects to create natural highlights. This usually puts faces in shadow so I sometimes carry a 16×20″ white card to lighten up some shadow areas. Or, I will sometimes use the camera’s built-in flash. This will provide just enough light to fill in the shadow areas. Or, if I’m on an actual assignment, I will bring some portable lights with me to accomplish the task.

I like to begin lighting lessons, especially with more than one light, by using hot light bulbs because you can readily see the effect of position, intensity, angle, etc. WITHOUT TAKING A PICTURE!  This forces you to THINK about what you are doing when you set up your lights. There are many photographers who set up a multiple light set without really thinking about what they are doing. Those results will always be disappointing.

Here’s a good example of a simple, two light set up used to fill in shadows caused by the main light:

This is a typical REMBRANDT LIGHT with a fill-in light added. The shadows are there, but they are transparent, light gray. You can still see the shadows, but there is plenty of detail in them. Note also that the background is dark because there is no light on it. We will get to that in subsequent articles. All we did here was to add a SECOND LIGHT to the arrangement. Here’s what it would look like without the fill-in:

The basic lighting arrangement is there with the one light, but the shadows are dark with just about no detail. This might be okay for a dramatic kind of portrait, but it wouldn’t work for any commercial use. 

Here is another studio example:

The reason for adding extra light is to provide more detail or to separate the subject more from the background. These techniques always make for more interesting images and also make them stand out more from simple snapshots. So you need to decide how much information you want to show and how dramatic you want your image to be. Then you can add your second light with purpose. 

With all this being said, it is important to note that when you are using natural light, or other light you cannot basically control, you can simulate the effects of a second light in a studio, by using the ambient light you have at your disposal and use a reflector card or a small, portable flash to fill-in shadows. The goal should be just to lighten shadow areas enough without actually lighting the scene with the second light source. Here is an example:

This image was made by allowing the sun to provide highlights on the subject while using the second light to provide just enough fill-in to show some detail in the shadow areas. Remember, the idea is to FILL IN the shadows.

These techniques utilize the concept of the fill-in light for natural light photographs as well as those made in the studio setting. The concept of “filling in” the shadows is something we all should be aware of every time we shoot anything.