How Light Behaves – Update

Note: This is an article I published several months ago. I have updated it and the ideas bear repeating.

How Light Behaves

by William Lulow

As photographers, we are always aware, or at least should be, about how light behaves. Light is one of those elements, kind of like electricity that we know is there, AND we can see it. It is all around us, even at night. Electricity is around us but we can only see the effects of it. Light can do some amazing things.  What it does best is to enable us to see things around us. I always tell my students of lighting for photography that once they study classical portrait lighting setups, they will never again be able to view any photograph without noticing the lighting! The same is true of how light affects the world around us. Once you are aware of how artificial light is applied in the photographic process, it will become almost impossible to view any natural lighting phenomenon without being acutely aware of it. One case in point here are sunsets. Everyone goes “ooh” and “ahh” when they see particularly beautiful sunsets maybe without realizing how nature produces them. You see, the sun we all know, is stationary. When the earth revolves on its own axis, it makes the sun appear to move. When the earth turns so that the sun appears very low in the sky, the atmosphere bends those rays a lot so that the part of the visual spectrum we are seeing is more to the reds and oranges. When the sun appears high in the sky, the earth is at that point in its rotation where not a lot of bending of light rays is happening. In other words, at noon, there isn’t much refraction of the sun’s rays. In the evening (and in the early morning), the sun’s rays are refracted or bent a great deal. The reflections produced by the low angle of light is what makes the scene spectacular and catches the eye.

So, the same is true about anything that’s highly reflective or light. Our eyes are quickly drawn to it because it produces a highlight, or white light, when we view it. Here’s another example of something light in an image:

This is an example of an EDGE LIGHTING. Note how the highlight reproduces as white against a black background. That’s what draws the eye to it and makes it stand out.

The effect of light on any subject is all about its intensity. The closer it is to the subject, the more intense it is. Obtaining the correct balance between the amount of light produced and the exposure to reproduce it, is what lighting for photographs is all about. First you need the ability to “see” lighting and its effects, then you need the ability to render it the two-dimensional format of an image.

As I said, light as we know, is all around us, even at night. There are very few places on our planet that are not lit at night by artificial light, mostly created by electricity. We have become totally dependent on electricity and the power it takes to create it. This is one of the reasons that an understanding of artificial light and how it behaves is really necessary if you plan to do any kind of photography. Light follows what is referred to as the “Inverse Square Law.” This basically says that the intensity of the light varies inversely as the square of the distance between light source and subject. Another way to understand this is that if you take a lamp and place it say, ten feet from your subject, then move the light half that distance closer to your subject, the intensity of the light will be twice as bright. Conversely, if you move that same light twice the distance away (20 feet), the intensity of the light will be HALF of what it was! (It follows a geometric progression.) So, we are talking here about how light is reproduced in a photographic print or digital image. Knowing how light behaves is one of the most important elements in the creation of good images.

Light reflected off of ominous clouds or on a couple of beach chairs on an empty beach evoke a somber mood and add drama to an otherwise mundane image.

Learning about artificial light enhances your ability to recognize how shadows can be used to draw more attention to areas that the sun lights. It can almost be like you are manipulating natural light to imitate what you know about studio lighting by choosing camera angles and positions that can reveal both the shadows and highlights. Then you use what you know about exposure techniques to render what you see in two dimensions.

So, when you are out in nature, the more you know about how light behaves, the better able you will be to recognize light patterns and its characteristics. When you are constantly on the lookout for lighting that you are already aware of, you will be better prepared for its behavior and consequently, your ability to recognize really dramatic lighting will almost automatically, make your images better.