Understanding Light for Better Portrait Photography

A solid understanding of light can make you stand out from an average photographer. In fact, in portrait photography, light is even more important than the subject and location. This is because without the proper use of light, you can ruin the shot, even with the best looking subject, at the most awesome location in the world!

In this article, I’m going to break down the understanding of Light for you into six simple terms. Once you understand and apply these concepts, you will immediately notice the improvement of quality in your portrait photographs.

The six principles of light are: intensity, dynamic range, direction, diffusion, White Balance and reflection.

1) Intensity of Light

Intensity is the brightness level of light and it brightens up your subject. For both natural light and studio light, you can modify the light source to change the intensity. I’ll cover the basics of light modifiers later, but the most important fact about intensity is that the distance between the light source and your subject has a massive impact on the intensity of light.

This is also known as the Inverse Square Law.

It is an equation that dictates the intensity of light produce at a given distance. It states that the intensity of light changes in inverse proportion (one over that number) to the square of the distance from the source. Meaning:

• At one foot it is 1 over the square of one or 1/1 or 100%
• At two feet it is 1 over the square of 2 (2×2) or ¼ or 25%.

In plain English, that means if you double the distance from one to two feet, the light intensity will decrease by 75%. On the other hand, if you bring the light source closer from two feet to one foot the intensity of light is going to increase by four times.

With the knowledge of inverse square law, you will be able to determine the placement of your subject for better portrait photography.

2) Dynamic Range

Dynamic range and stops have a very close relationship. Dynamic range is the difference between the lightest and darkest tones of an image, and a stop is the measurement of this range. Since a stop measures light in representation of numbers, what’s the relationship between the two?

The difference of one stop of light means the light is twice (or half) as intense. Human eyes can detect roughly 10-14 stops of light, while a DSLR camera can only detect around 8-10. With that said, your camera sees a lot less than your eyes. Dynamic range issues occur when this range goes beyond what the camera can record in details. These areas come out as pure white or pure black in the photograph.

Generally, most people tend to avoid pure white and black in portrait photography unless it is for artistic reasons. Otherwise, it may look like as if you exposed the picture incorrectly.

3) Direction of Light

The position of your light source is very important because it determines how light hits your subject. It has a great affect on the quality of your photograph and a few small inches of light misplacement could bring your shot down to a snapshot.

A common question people always ask is, “Why do I need to worry about the direction of light when the subject is properly exposed?” Everyone has different opinions, but my point of view is that this is how you create mood, define shadows, and shows depth to your subject.

The biggest thing to avoid in portraits is flat images (which is created by lighting your subject directly from your camera angle). Reach into your wallet now and grab your driver’s license. That is an example of a flat image. The picture is either too bright or too dark; there is no shadow on your face (or a very harsh one) because the flash was pointed straight at you; and the worst thing is you probably look 10 years older! Without saying any further, I am almost certain that it is one of the worst pictures of yourself.

So what are some ways to light your subjects? Below are two of the most common ways:

Split Lighting – This direction of light divides the face equally in half so one side is in shadow while the other is toward the light. You can simply place the light source 90 degree to the left or right of your subject. If you are using natural light, just ask your subject to turn to such an angle. It creates a very deep dramatic shadow that casts strong moods for your subject. It is great for artistic type portrait shots.

Loop Lighting – Perhaps the most common lighting method for portraits. Simply place the light source about 45 degrees to your subject. The shadow it casts is going to show nice depth; this method is great for single portraits. Make sure you place the light just slightly above eye level to make the best of this lighting style.

There is no right or wrong direction of light in portrait photography. They are more personal preference, mixed with different style and purpose. The main thing is that you make your subject look good in front of the camera.

4) Diffusion of Light

Diffusion relates to hardness and softness of light. It also determines the intensity of the shadow. As a general rule, the bigger the light source and the closer it is to the subject, the softer the light.

When photographers talk about hard light, it means there is a rapid falloff between bright and dark areas in the photograph creating harsh, sharp-edged shadows. As such, the photograph doesn’t look as appealing to the viewer.
An example of hard light would be taking picture under a bright sunny day or when you overexpose studio light photographing your subject. Generally, hard light is not something you should be looking for in portrait photography unless for artistic reasons.

As you might have guessed, opposite hard light, there is soft light. This kind of light has mild falloff between bright and dark areas in a photograph. The light is evenly spread and it looks like it wraps around the subject.
An example of soft light would be taking pictures under an overcast day or using studio light with modifiers. The portrait looks more pleasing to the viewer and the photograph does not show much contrast.

5) White balance

White balance is the color temperature of your camera’s setting. Matching the right color temperature in the environment you are shooting is very important. This is how you remove an unrealistic colorcast, so that your photograph represents true color that you see in real life.

Depending on your camera model, you should have a different white balance presets to choose from: Tungsten, Fluorescent, Daylight, Flash, Indoor, Cloudy, Shade, Custom (PRE), and Kelvin (K).

As the photographer you need to make sure white appears white and not yellow/orange on the hot end, and blue/green on the cold end on the Kelvin scale.

If you shoot RAW, you can modify the white balance during post-processing of your images. This can also be changed easily in Adobe Lightroom or Photoshop. By the way, this is one of the reasons why it is important to shoot RAW instead of JPEG.

6) Reflection of light

Light has one very distinct behaviour; it travels in straight lines. Which means no matter whether you are using natural light or studio light, it is only going to travel in one direction until it reaches a surface.

Once the light reaches a surface it reflects off at the same angle it hits. The amount of light being reflected is going to be determined by the color and texture of the surface.

So why is reflection of light important for portrait photography?

Once you understand light behaviour you can then modify it to control how much light you want for your subject. For example, if you want soft light and you have no other equipment, you can bounce light off a wall. As mentioned before the larger the light source the softer the light, you can now control both the direction and intensity of light for your portrait photographs by doing so.

Another common way to modify light is using a softbox such as a brolly box (umbrella softbox). This is a type of softbox where the external flash is placed inside of it. When the flash fires, light bounces all around inside the box until it exits out the white diffuser on the front. If you have an assistant to hold the brolly box you now have a portable light source producing soft light everywhere you go. This is a must-have for portrait photography.

I hope by breaking down the understanding of light into six categories they are going to be able to level up your skills as a portrait photographer. Be sure to practice as much as you can, but most importantly, enjoy this process and have fun in photography.