How to Use Fill Light in Photography

What is fill light in photography? Why is it so important when shooting portraits? And how can you use it to capture more refined, professional images?

Fill light is one of those essential skills that every portrait photographer should master, whether they prefer natural or artificial light. In fact, as a professional portraitist, I use fill light all the time in my own work. Over the years, I’ve developed plenty of tips and techniques for beautiful use of fill light – and in this article, I lay them all out. Here’s what you can expect to learn:

What fill light actually is (in simple terms)
Why fill light will improve your portraits so dramatically
Easy ways to generate fill light in any situation
How to position your fill lights for flattering results

I also include plenty of examples, so you know exactly what fill light is capable of. By the time you’re done, you’ll be ready to shoot some stunning fill-lit portraits of your very own!

Let’s get started.

What is fill light in photography?

Fill light illuminates any unwanted shadows in a portrait. It’s a form of supplementary lighting you can add to any lighting setup, and it works alongside the primary lighting – that is, the key light – to create a flattering effect.

fill light photography example portrait of a woman with fill applied — Fill light will give you complete control over the contrast and tonality in your images. If you can master fill light, you’ll be *unstoppable*!

More specifically, fill light:

Enhances details in the shadow areas of an image
Reduces the overall contrast in the frame
Brings the final image more in line with how the eye sees the world (as opposed to the more limited view of the camera sensor)

Take a look at the two images below. The shot on the left lacks fill light, so the back of my subject’s dress is completely black. When I add a bit of fill light behind the subject, however, the dress gains detail and you get a more natural result:

a before and after portrait of a woman — The image on the left has no fill light; the image on the right includes fill light on the subject’s back; as a result, there’s a lot more detail on the back of the dress, as well as under my subject’s arm.

Now, you might be wondering:

Do you need to include fill light in every portrait photo? What if you want a dark, moody, contrast effect?

No, you don’t need to always add fill light to your images. Dark and contrasty images definitely have their place (I love them, myself!). However, fill light will create portraits that look more even and natural, so if you’re working with clients, I highly recommend it, even if the effect is very subtle. (The possible exception would be when your client is looking for something more artistic – but even then, fill light can help you better achieve the look you want.)

fill light final portrait — One of the final portraits from the shoot. Note how the far side of the model’s face is relatively dark, *but* there’s still a touch of detail thanks to the fill light.

Two simple ways to create fill light

While you can technically create fill with any method of illumination (including flashlights, neon signs, and even phone screens), there are two tried-and-true methods of filling in a portrait that I suggest for beginners:

1. Reflectors

Reflectors are the simplest, cheapest, most basic method of creating fill light. They’re also highly versatile.

A reflector is just a piece of reflective material – often white, silver, or gold fabric or card – so by positioning it carefully, you can bounce your main (key) light back into the shadows for a diffused fill effect.

Here’s a reflector fill light example. Note how my key light is on the subject’s left, while my reflector is positioned on the right to bounce some light onto the darker side of the subject’s face:

behind-the-scenes image with fill light reflector

If you’re new to portrait photography, a reflector is often a great way to delve into fill light photography. For one, a high-quality reflector will only set you back a few dollars (you can even make one yourself using white cardboard or bedsheets). Plus, reflectors are very easy to position, they’re quick to set up, and they require a minimal learning curve, as you simply need to move the material back and forth next to your subject.

The biggest drawback to using a reflector for fill is that it’s not very flexible; since you’re completely reliant on the key light for illumination, you’ll need to work with its positioning – and intensity – to create the fill-light effect you want.

2. Flashes or studio strobes

You can always use one (or two, or many) standard speedlights or studio strobes as your fill light, in addition to your key light.

A dedicated fill light will do the same basic job as a reflector, but it is infinitely more controllable: You can fine-tune the exposure and shape of your fill light with a precision that reflectors just don’t allow.

However, if you’re currently working with a one- or two-light setup, you may need to shell out for an additional light, which can be pricey. Plus, the learning curve is more significant; a strobe fill light offers plenty of power, but you must learn to adjust the flash output and apply the right modifiers for the effect you’re after.

Ultimately, the choice of fill light is up to you. If you’re serious about leveling up your skills fast, then feel free to go with the strobe. But if you’d prefer a simpler, more gradual path, a reflector might be the better option.

using a strobe as a fill light behind the scenes

If you do decide to use a speedlight or studio strobe for your fill light, you’ll generally want to make sure that you’re diffusing it with a large modifier. Large softboxes and octaboxes offer a nice fill quality and plenty of flexibility, but they’re also expensive and more cumbersome to work with. Umbrellas, on the other hand, can produce beautiful light for cheap, and they’re easy to use in smaller spaces, but they tend to just throw light all around the room, which isn’t always ideal! Over time, you’ll likely want a collection of fill-light modifiers so you can pick the right tool for the job, but when you’re just getting started, you’ll want to make a careful purchase based on the type of images you plan to shoot as well as space and budget considerations.

How to master fill light photography: tips and techniques

In this section, I offer my favorite methods for working with fill light. Most of these techniques apply to both reflector and strobe fill lighting, but I indicate up front where the techniques are only applicable to one method.

1. Start by understanding lighting ratios

Lighting ratios might sound technical, but they’re really not. A lighting ratio simply tells you how bright one light is in relation to another light.

So if your key light is twice as bright as your fill light, the lighting ratio is 2:1; if your key light is four times as bright as your fill light, the lighting ratio is 4:1; and if your key light is eight times as bright as your fill light, the lighting ratio is 8:1. The greater the lighting ratio, the more contrasty (and dramatic) the resulting effect:

different lighting ratios applied to portraits — Left: The shadows are heavily filled, thanks to a 2:1 lighting ratio; this creates a low-contrast image.
Right: The lighting ratio is 16:1, which creates a contrasty image with deep shadows (though all of the detail is still present!).

Note: Fill lighting will always be underexposed in relation to your key light. If it’s even to your key light (i.e., if you have a 1:1 lighting ratio), you will get flat, no-contrast images as a result, which is rarely ideal. Instead, you want your fill light to be at least one stop darker than your key light.

How do you set this up? The easiest way is to use a handheld incident light meter. Take a test shot while metering off your key light, then take a second shot while metering off your fill light. Compare the two exposure values. Because a single stop of exposure corresponds to a doubling (or halving) of the light, a one-stop difference between the two lights indicates a 2:1 lighting ratio, a two-stop difference indicates a 4:1 lighting ratio, a three-stop difference indicates an 8:1 lighting ratio, and so on. Then you can adjust your lighting and re-meter until you get the result you want.

If you don’t own a handheld light meter, I’d recommend simply eyeballing the scene, and then adjusting your lights accordingly. The ratios are there to help, but they’re not an essential part of fill-lit portraits.

Just remember: The greater the difference between the key light and the fill light, the higher the contrast. So if you want less contrast, set your fill light one to two stops under your key light. If you want more contrast, go with three to four stops.

2. Use the right approach when adding a reflector as a fill light

portraits with reflectors as fill — Reflectors can create plenty of effects when used as fill. They’re impressively versatile, especially when you consider what they are!

If you’re set on using a strobe as a fill light, then you can skip this section – but as I emphasized above, reflectors are a great way to get started with fill lighting, and they’ll get you outstanding results with very little work.

Here’s what I recommend:

First, set up your key light so that it’s shaping and lighting your subject as desired. It’s a good idea to use a standard lighting pattern, especially as a beginner (e.g., loop lighting or butterfly lighting). Meter off your subject and determine the ideal exposure settings for your image.

softbox lighting a woman — Here, I positioned my softbox as a key light roughly in front of and above my subject.

Next, evaluate the shadow areas that your key light is creating. If you’re using natural light, continuous lights, or strobes fitted with modeling lights, you can do this by eye. Alternatively, you can take a test shot and review it on the back of the camera.

softbox test shot — Here’s my test shot. While the lighting is soft, the shadows are very deep.

Third, place your reflector so that it’s roughly opposite your key light. In the next image, you can see that I’ve positioned my reflector close to the subject’s waist, pointed upward:

adding a reflector beneath the subject — Adding a reflector beneath the key light raised the exposure in the shadow areas of the image.

For a low-contrast effect, bring your reflector in as close as possible. For a higher-contrast effect, move it away. Once everything is in place, evaluate the effect of the reflector (either by eye or with a second test shot).

The goal is to bring up the shadows without eliminating them. If your shot looks good, then go ahead and start shooting. If your shot is too contrasty, then you’ll need to move the reflector closer and take a third test shot; if your shot is too low-contrast, then you’ll need to move the reflector farther away (and, of course, take another test shot!).

portrait with fill light — Here’s my final result. The shadows are still present, but – thanks to the reflector – the overall contrast in the image has been reduced.

It can take quite a lot of practice before you learn to see the subtle changes a white reflector provides. The key is to shoot as much as possible and spend time observing the different effects created by various reflector positions.

If you’re struggling to evaluate the effects of the reflector and you want to get better, fast, do this simple exercise: Start with a distant reflector, then move it closer to the subject, taking shots as you go. Compare the shots on a large monitor and try to see the difference between each setup. Pretty soon, you’ll notice even the most subtle shifts in the light!

3. Learn to work with a second light

images with adjusted fill light — You can create varying degrees of contrast between your shadow and highlight tones by adjusting the power of your fill light.

As you become an advanced portrait artist, you’ll probably want more control over your lighting. That’s where strobes come in handy; while they’re harder to use for fill lighting, they do offer more control.

man with a strobe as fill light — A second strobe serving as fill gives you maximum control over your shadows.

To get started with a dedicated fill light, place your key light in the desired position, set the power, and determine the proper exposure. (For the sake of instruction, I’m assuming that your aperture is set to f/8 and your shutter speed is set to a fixed 1/200s.) Take a test shot.

behind the scenes image with softbox and woman — I’ve placed my softbox 45 degrees from the subject.

Using your test shot as a reference, place your fill light so it’ll beam light into the main shadow areas on your subject. Set the power output so that the light will be underexposed.

(How much you underexpose is entirely up to you! If you want a stop of fill, then you can adjust the power until you get a proper fill light exposure of f/5.6. If you want two stops of fill, then adjust the power until you get a proper fill light exposure of f/4. Of course, if you cannot calculate the exact aperture amounts via a handheld light meter, then just eyeball it!)

adding a second light — I added my second light – modified by a parabolic umbrella – about 10 feet away. I set the exposure at two stops under the key light.

Take a test shot and see if you get your desired effect. If the result is too contrasty, then increase the fill light’s power output; if the result is too even, then decrease the fill light’s power output. Make sense?

Here’s my final result (right) compared to the image before I added the fill light (left):

before and after with fill light — Note how the shadows are still present *but* the result is more detailed and less dramatic.

4. Learn to work with multiple fill lights (and think outside the box!)

Basic fill light setups require a single light, but you don’t need to limit yourself. You can use multiple fill lights in a single shot to illuminate your subject from different directions. You can also mix lights and reflectors for different fill light strengths.

woman standing in a studio with lights all around — You can design fill lighting however you like. Feel free to use multiple light sources in different sizes and shapes!

Once you start to feel restricted by the basics, it’s really just a matter of experimenting. Ultimately, you can do whatever you want when creating a lighting setup. You’re only limited by the equipment you have at hand and your own imagination.

multiple fill lights woman portrait — Using multiple fill lights allows you to control every bit of contrast in your images.

Also, don’t be afraid to think outside the box. I’ve discussed the two most popular methods of fill lighting – reflectors and strobes – but any light source can be your key and your fill. You can even use natural light as fill while your main light is provided by flash.

woman lit by a window — Here, the key light is a large window to camera right. The fill light is provided by a strobe. You can mix light sources to achieve your fill lighting!

5. Pay attention to your catchlights

Here’s one final tip for you, and it’s a big one:

Catchlights – that is, the spots of reflected light that appear in your subject’s eyes – matter a great deal. Images with zero catchlights look terrible, but images with too many catchlights, or oddly positioned catchlights, can also look bad.

If you’re struggling to achieve any catchlight at all, then your light sources are too far behind your subject, and you need to move them forward (or have your subject tilt their head) to achieve the right reflective angle.

This portrait features a single clear catchlight at the top of the eyes.

However, if your subject has one or more catchlights but you don’t like the look, you’ll want to make other adjustments. Consider repositioning some of your lights so they no longer reflect in the eyes, or switching modifiers to create different shapes, or adjusting the light outputs and positions so they reflect at different intensities and in different parts of the eye.

Bottom line: As you set up your lights and reflectors, check your subject’s eyes. Make sure the catchlights look flattering. If necessary, adjust the lights until you get the effect you want. Only then should you move on with your photoshoot.

Fill light in product, still-life, and food photography

Throughout this article, I’ve discussed the power of fill light in your portraits, and I’ve offered various portrait fill-lighting examples. But it’s important to emphasize that fill light is not just restricted to portraiture. You can use fill light to enhance any type of photo, especially product photography, where you’re often working in a controlled environment and need to carefully balance the lighting on the subject.

Still-life and food photography are two other genres where fill light can be hugely helpful. You can use that second light to fill in shadows for a beautiful effect!

Fortunately, my approach to shooting with fill light is broadly applicable – so even if you don’t do portraiture, you should still be able to capture amazing photos by following the instructions I’ve shared above!

Fill light in photography: final words

Hopefully, you can now confidently get started with fill-lit images. Controlling the contrast in your images is a fundamental skill, and it’ll instantly give your images an extra level of depth.

So do some practicing. Start simple and go slow, and pretty soon, you’ll have mastered the basics!

Now over to you:

What type of images do you plan to capture using fill light? What setups do you plan to try first? Share your thoughts in the comments below!