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.