Fill Light Photography: Your Essential Guide

by John Stapel

A Post By: John McIntire

how to use fill light in your photos

What is fill light photography? And how can you use fill light to achieve stunning portraits?

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 it all out:

  • A simple fill lighting definition
  • Why fill light is so important for portrait photos
  • Two easy ways to generate fill light in any situation
  • How to position your fill lights for flattering results

I also include plenty of fill light examples, so you know exactly what it can do. By the time you’re done, you’ll be ready to shoot some stunning portraits of your own.

Let’s get started.

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!

What is fill light in photography?

Fill light is light used to illuminate (fill in) the shadows in a portrait. It’s a form of supplementary lighting you can add to any lighting setup, which works alongside the primary lighting – that is, the key light – to create a flattering effect.

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.

Now, you might be wondering:

Do I need to include fill light in every image? What if I want a darker, moodier, contrasty effect?

No, you don’t need to always add fill light to your photos. Dark and contrasty images definitely have their place (I love them, myself!). However, fill light makes portraits look more even and natural, so when working with clients, I highly recommend it, even if the effect is very subtle.

fill light final portrait

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 a piece of reflective material, 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, with my key light on the left and my reflector positioned on the right:

behind-the-scenes image with fill light reflector

If you’re new to portrait photography, a reflector is often the way to go. For one, a high-quality reflector will only set you back a few dollars (you can even make one yourself using white cardboard or sheets). 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.

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

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.

handheld light meter A light meter is the easiest and most accurate way to evaluate lighting ratios. However, they’re not cheap!

If you don’t own a handheld light meter, I’d recommend simply eyeballing the scene, 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. Add a reflector as your fill lighting

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 second 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. Meter off your subject and determine the ideal exposure settings for your image.

softbox lighting a woman Here, I got started with my softbox as a key light.

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. For a low-contrast effect, bring your reflector in as close as possible. For a high-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).

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

The goal is to bring up the shadows without eliminating them altogether. 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 even, then you’ll need to move the reflector farther away.

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. 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

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. Images with zero catchlights look terrible, but images with too many catchlights, or oddly positioned catchlights, can look equally bad.

woman with clear catchlights headshot This portrait features a single clear catchlight at the top of the eyes.

So as you set up your lights and reflectors, check your subject’s eyes. Make sure the catchlights look flattering. If necessary, adjust the light outputs and positions until you get the effect you want. Only then should you move on with your photoshoot.

Fill light in photography: final words

Hopefully, you can now confidently get started with fill-lit portraits. 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 portraits do you plan to capture using fill light? What setups do you plan to try first? Share your thoughts in the comments below!

Fill Light Photography: Your Essential Guide

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John McIntire

John McIntire

is a portrait photographer currently living in the UK. He studied commercial photography and is always looking to improve. Admittedly a lighting nerd through and through, John offers lighting workshops and one-to-one tuition to photographers of all skill levels in Yorkshire.

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