Using a single light source can cause ugly shadows and exposure problems. A fill light helps to balance the light and gives you more control over your result. It also allows you to regulate the light ratio.
Read on to find out how to use a fill light!
[Note: ExpertPhotography is supported by readers. Product links on ExpertPhotography are referral links. If you use one of these and buy something, we make a little bit of money. Need more info? See how it all works here.]
What Is a Fill Light Used For?
Fill light photography uses a second light source to fill in shadows and help balance the exposure. This lighting technique is especially useful when there’s a strong backlight.
Fill light is most often from a flash, strobe, continuous electric light or reflector. The light value of fill light on a subject is less than the light value of the main light.
The main light source is always the brightest light in any lighting combination.
Why Should You use a Photography Fill Light?
In situations when you have a single, bright light source, it’s often a good option to use a fill light. This is most common outdoors on a sunny day.
The sun will cast dark, hard-edged shadows on your subject. Adding a secondary light such as flash or using a reflector will soften or remove these shadows. It will fill them in with light. The result can mean a much more flattering portrait.
Adding a photography fill light will bring balance to the lighting. You can render your subject the same exposure as your background by adding in the correct amount of light.
Set the Fill Ratio for Best Results with a Fill Light
The key to effective use of fill lighting is to set the correct fill ratio. To do this make an exposure reading from the lightest part of your composition.
This could be your subject’s face where it’s in the sun, or it may be the background. Using your spot meter or camera monitor with your camera set to manual mode will allow you to manage your settings well.
Once you have determined how much available light there is you can add in as much light as you need for the shot.
Sometimes you might want to balance the fill light to the available source of light. This will eliminate the shadows on your subject’s face altogether.
In this photo below, I used a flash bounced off a reflector as my main light which was to my right. I added light from a small softbox on my left as the fill light.
The fill light was set to give slightly less light than the main light, so there are no dark shadows. Balancing the light ratio so closely results in a fairly flat looking portrait.
Having your fill light providing one or two stops less light than the main light will leave some shadows on your subject. Filling in some of the shadows will create more depth in your portrait.
For the next portrait, I had a small softbox on a stand to the right of my subject and slightly in front of her. I made an exposure reading of the ambient light and set my flash to output a slightly higher ratio.
This left some soft shadow on the left side of her face.
It’s essential to decide how much fill light you want to add to your portrait to get the look you want. It’s common to see portraits where too much fill light has been added. It overpowers the main light.
This can cause some areas of your composition to be overexposed. It can also create ugly dark shadows from your flash.
Control Fill Light Using a Flash
Using a flash on the manual setting allows you to have control over the amount of output, regardless of the ambient lights.
When you use your flash in any of the auto modes the flash and camera will determine the output. This calculation is made partly based on how much ambient light there is.
Sometimes you will not be able to achieve the results you want, or the flash output will vary when you alter your composition.
Manage your auto flash settings with its exposure compensation settings. This is similar to controlling the exposure compensation when using auto modes on your camera. You can dial in to force the flash to either underexpose or overexpose.
Don’t be too focused on getting the ‘correct’ exposure by the numbers. Pay attention to your monitor and histogram to see the effect your fill light is having.
Studying the image on your monitor is helpful in determining the best fill lights ratio.
Using a Reflector as a Fill Light
Portable foldable reflectors are a popular means of adding a fill light to a portrait. They provide a different feel of light than a flash will, but can be challenging to control. Many reflectors have a selection of surfaces you can choose to get the look you want.
The best way to use a reflector for portrait lighting is to have an assistant who understands what they need to do. Spend some time educating an assistant as to how to manage the reflector and see what they are doing with it. This will save you stress when you are taking your portraits.
Choosing the best reflector surface and having it at the right angle will provide a good photography fill light on your subject. Too much light reflecting can result in poor exposure and a squinting subject.
I find it’s helpful to tell my subjects to look away from the reflector, so they don’t hurt their eyes.
Having your assistant stand in the right place with the reflector will provide the most appealing portrait lighting. Opposite the location of the main light source is often the best place for a reflector.
With a reflector, you can see the light on your subject and observe the ratios before taking a photo. A reflector is bigger than a flash. It will provide a softer light, especially from a non-shiny surface.
Choose the Best Quality for Fill Light Photography
Using an unmodified flash can produce unflattering results. Even if you balance your fill light ratio beautifully, a bare flash will reflect off the skin. The resulting hot spots are pretty ugly.
Bouncing your flash or using a modifier to soften it will help you make more flattering portraits. My preferred method of modifying my flash is to use a small softbox.
It makes working a bit slower, but the soft light from the softbox is worth it. Compared to a bare flash, the light from the softbox is much more gentle and appealing.
Careful choice of the right surface on a reflector is important. In bright sunshine, I don’t use the gold or silver reflectors as they bounce too much harsh light onto my subject.
Using a flat white surface in bright sunshine will bounce soft light onto my subject.
In overcast conditions using the shiny gold or silver surfaces will help you achieve a soft light and a good ratio for your fill light source.
Often, two lights are better than one. The key is learning to control the output so you can achieve the desired ratio. Keeping your fill light lower than your main light will leave a little shadow on your subject. This can help create some depth.
Look for naturally reflecting light to use in your photos. I love doing this with street photography.
Know the look and feel of the light you want. With a well-controlled fill light, you can control the shadow and the mood of your portrait. We have great posts on how to use a key light, hair light, or rim light to check out next!
Use our Quick Capture Cheat Sheets on your next shoot for more handy tips!