Lighting is critical in film and photography. Not just because you'd see nothing if the scene wasn't lit, but the clever use of lighting adds to the tone and mood of the scene. Judicious use of light creates a focus whereas an abundance of light can create a mood of euphoria or simply a cheesy shot. Brightly lit scenes can look superficial.

It is important to know, before you continue, that as with every rule in art, knowing when to break it is as important as remembering the rule itself. 

Resources and Useful Sites

3-Point Lighting

Three-point lighting is a common technique for interviews and scenes where the person being shot/filmed is the key focus. There is no set formula for how three-point lighting is used. This often depends on the scene, the subject matter, and the overall mood that a cinematographer or photographer wants to evoke.

• Good lighting creates a more interesting and dynamic image where the subject is seen with more dimension and where the cinematographer has more control over shadows.

• The lighting setup helps bring dimension to characters. Three-point lighting also helps shape a subject to bring out the best or worst of them.

• By placing a soft key light slightly off center with a 2:1 fill ratio, a cinematographer creates a soft, flattering look that also tends to hide blemishes in the skin when your subjects are people. This soft lighting is called “high key lighting” and creates an optimistic, upbeat, youthful, light, and airy mood that is common in sitcoms and comedies.

• If a cinematographer opts for a higher fill ratio, like 8:1, the key light casts sharp-edged shadows that contrast sharply with the light. This is “low key lighting,” which creates a dramatic, mysterious, unsettling, and alienating mood and can display a range of deep negative emotions. As such, it is common in dark dramas, thrillers, horror, and film noir.

Key Light

The key light, as the name suggests, shines directly upon the subject and serves as its principal illuminator; more than anything else, the strength, color and angle of the key determines the shot's overall lighting design.

In indoor shots, the key is commonly a specialised lamp, or a camera's flash. In outdoor daytime shots, the Sun often serves as the key light. In this case, of course, the photographer cannot set the light in the exact position they want, so instead arranges the shot to best capture the sunlight, perhaps after waiting for the sun to position itself just right.

Fill Light

The fill light also shines on the subject, but from a side angle relative to the key and is often placed at a lower position than the key (about at the level of the subject's face). It balances the key by illuminating shaded surfaces, and lessening or eliminating chiaroscuro effects, such as the shadow cast by a person's nose upon the rest of the face. It is usually softer and less bright than the key light (up to half), and more to a flood. Not using a fill at all can result in stark contrasts (due to shadows) across the subject's surface, depending upon the key light's harshness. Sometimes, as in low-key lighting, this is a deliberate effect, but shots intended to look more natural and less stylistic require a fill.

In some situations a photographer can use a reflector (such as a piece of white cardstock mounted off-camera, or even a white-painted wall) as a fill light instead of an actual lamp. Reflecting and redirecting the key light's rays back upon the subject from a different angle can cause a softer, subtler effect than using another lamp.

Backlight

The third source in this lighting technique, the backlight (also known as the “rim light” or “hair light”) shines on a subject from behind, completing the light setup. This creates a rim of light or outline around their head that pushes the subject away from the background and gives a sense of depth. Typically, cinematographers position the backlight directly behind the subject or high enough to be out of frame, opposite the key light, and pointing at the back of the subject’s neck.

Four-Point Lighting

Four-point lighting utilises an additional “background light” to illuminate what is behind the subject. Unlike the backlight, which creates a ring or an outline of the subject, the background light illuminates background elements, such as walls or outdoor scenery.

Cinematographers use this technique to eliminate shadows cast by foreground elements onto the background or to draw attention to the background. The fourth light also helps the camera give depth to the subject. 

To achieve the look, the cinematographer positions a background light behind the subject, either low to the ground or on a high grid, facing toward background elements, such as walls or outdoor scenery.

5 Tips for Setting Up Three-Point Lighting

There are several key components to successfully setting up three-point lighting and creating a polished, professional video.

1. Establish your light’s “motivation.” 

Before you begin setting up your lighting kit, you have to know precisely what look you want to achieve and why. Lighting setups are never random. The source of light in your scene needs to make sense based on the environment that your characters exist in. Is it an overcast sky? Sunset? A dark alley? Once you have established the motivation, you can proceed to place and adjust your light kit to achieve that effect. (You may also want “unmotivated” light. In horror, having unnatural light gives the sense that something is off and unsettles viewers. You must still establish that beforehand.)

2. Consider light source size and distance. 

The size of a light source relative to the subject size determines how “hard” (sharp, distinctive edges) or “soft” (smooth, feathered edges) your shadows will be. A smaller light source creates harder, distinct edges, while a bigger one softens the shadows. In studio lighting, if you want a softer look, you place enlarging modifiers such as an umbrella, softbox, or another diffusion between the light source and the subject. Due to this relative size condition, the distance of the light source to the subject will also affect shadow softness. If you put the source closer to the subject, the shadows will be softer. The shadows will be harder if you pull the light back from them, making the relative size to the subject smaller.

3. Consider the intensity of your light source. 

“Brightness” is the measure of a light source’s intensity. You measure it in lumens with a light meter. With LED lights, fluorescent lights, and incandescent lights, you control the output intensity, which affects the look of your scene. Brighter light will create harsher edges and shadows.

4. Consider the position of your light sources. 

Where you place your lights relative to your subject and the camera determines where shadows fall. This relates again to sensibly creating an environment—if your key light represents the sun, it should accurately reflect the angle and height of that source. How you position your fill and backlight affects whether there are deep, moody shadows or an optimistic, even light cast across your scene.

5. Test your setup.

After you have determined your lights’ motivation, their size, distance, intensity, and position, set everything up so you can see exactly how all the lights work together and whether or not their effect is precisely what you intended it to be. If it is not, make adjustments until everything is perfect.

Lighting Accessories

Diffusers & Scrims

When lighting, you often want to avoid sharp lighting contrasts such as the intensity from the light source. A diffuser is a cloth or plastic sheet that covers the light's output and makes it soft and diffused. You can also diffuse light by bouncing it off a surface or a reflector.

A softbox is a diffuser that fits over your light to distribute the light evenly. Sometimes, these softboxes will have an egg crate (mesh), that will force the light rays to go in a certain direction rather than scattered.

A downside of diffusers are that they do reduce the light slightly.

The scrim and diffuser are extremely similar, and many people might argue that there is no difference between the two. However, a scrim diffuser tends to have a large square shape and is attached to a metal frame that enables it to tilt forward and back to achieve the proper effect, and best of all, the metal frame makes it possible to use hands free. Conversely, a diffuser can be anything that scatters light, including a paper towel that you hold in your hand. Many diffusers also attach directly to another component, like a flash diffuser.

A scrim is good for scattering light to help reduce harsh shadows. Its large size makes it good for locations with plenty of light, like outdoor photoshoots, as you can use it to block the sun. Since it tilts, you can achieve the perfect gradient of light and use it without an assistant. The only downside is that the large size and steel frame can make it harder to transport.

Reflectors

Reflectors work similar to a diffuser to soften light, but have another purpose: to direct light elsewhere. Different coloured reflector surfaces can add warmth or colour to the light source. Reflectors are generally used where the light source is fixed or difficult to position. You'll see reflectors used in outside shoots, bouncing the light from the sun onto a subject.

Photographic studios also use diffusers for the flash, making the intensity of the flash balanced and not forming a hot spot (an area where the light is more intense) on a section of the subject.

The difference between a reflector and a diffuser is the direction of the light. If light bounces off a surface onto a subject, it's a reflector, whereas a diffuser spreads the light as it passes through.

Gels

A gel is a film that is placed over a light source to filter out wavelengths of light, letting through the parts of the colour spectrum we want. Gels have specific colours and modern RGB lights that can simulate gels allow you to set specific gel reproductions.

Neutral Density (ND) gels work like ND filters on a camera lens - they flatten the light in the same way as sunglasses. These can be placed over bright light sources to tone down the light, making it balanced with the interior light. They work by reducing the intensity of all wavelengths, or colours, of light equally from entering the camera in measured amounts. This allows the photographer or DP more control in selecting shutter speed and aperture combinations in a variety of conditions.

Flags

We've covered many ways to create and bounce light, but sometimes, you don't want any light. Flags are mounted fabrics and other materials that block light or shape light in a scene.  We often use the term negative fill when talking about flags, as they do remove portions of light from entering a scene. They can also protect the lens from a flare (barn doors).

Types of Lighting

So, you're on a set and the gaffer (in charge of lighting) asks you to set up a gobo on a fresnel, bounce it off a reflector and through a scrim. So far, from the information above, you'd be able to cobble together what they want. However, what when the production designer asks for some motivated light, or to source some practical lighting? Let's take a look at all of the lighting terms you might hear on a film shoot.

This NoFilmSchool article does a good at explaining this with pictures to boot, so take a look at this first.

lighting techniques used in film:

1. Key Lighting: Key light is the primary light source for your scene. The strength, colour, and angle of your key light is a determining factor to a cinematographer’s lighting design. The key light is most often placed in front of your subject, at an angle, and thus illuminates one section of your subject.

2. Fill Lighting: Fill light is used to balance out the key light by reducing the contrast and softening the shadows it creates. It’s typically placed opposite the key light and is usually softer and less bright than the key light.

3. Back Lighting: Backlighting is a lighting technique where a source of light is placed behind a subject, facing the camera. This technique illuminates the subject from behind, creating a rim of light that outlines its edges and separates it from the background.

4. Side Lighting: Side lighting is when the light source is positioned on one side of the subject in relation to the camera’s position. This lighting technique is used to bring out the textures or edges in a scene, creating a better sense of depth.

5. Practical Lighting: Practical lighting refers to the use of existing light sources within a scene to illuminate the environment and the characters. These light sources are integrated into the set design and serve a dual purpose: they provide both functional illumination and contribute to the visual narrative by providing realism.

6. Hard Lighting: Hard light is a quality of light that casts harsh and well-defined shadows. A subject or scene lit with this type of light has a very abrupt transition between the highlights and the shadows. Hard light typically comes from a relatively small source relative to the subject.

7. Soft Lighting: Soft light is the use of a diffused light source to create a more even and gentle distribution of light with less-defined shadows. Soft lighting creates a warm or dreamy atmosphere, making it effective in romantic comedies and dramas.

8. Bounce Lighting: Bounce lighting is about literally bouncing the light from a strong light source towards your subject or scene using a reflector or any light-coloured surface, such as walls and ceilings. Doing so creates a bigger area of light that is more evenly spread out.

9. High Key and Low Key Lighting: High-key lighting reduces the lighting ratio in the scene, meaning there’s less contrast between the darker tones and the brighter areas. Alternatively, low-key lighting has greater contrast between the dark and light areas of the image with a majority of the scene in shadow.

10. Motivated Lighting: Motivated lighting is a lighting technique in filmmaking that strives to make the light sources within a scene appear natural and justified. In other words, it mimics the way light would naturally interact with the environment and the characters within it. Put another way, motivated lighting is the technique used to imitate or accentuate existing light sources. Motivated light is commonly described as light within a shot that can be justified. This approach to lighting allows the audience to believe the world that they are seeing

Each of these techniques can be used individually or in combination to create a specific mood, highlight certain elements, or guide the viewer’s attention in a scene. The choice of lighting technique depends on the creative vision of the director and cinematographer, as well as the specific requirements of the scene.