Welcome to week two of my Learning to see Light series, where we cover the basics of light and how it relates to your photography. In this series, we are concerned with four attributes of light, Quantity, Quality, Color and Direction. This week we will focus primarily on the second attribute of light – Quality. As with any physical theory, I invite you to take the time to research further, this article represents my stance on quality of light. Now that the public service announcement is out of the way, lets go…
When discussing light, many photographers I know like to lump the quality of light and the color of light into the same topic. I personally like to have a significant separation in the two topics. To discuss the quality of light is to discuss it’s softness or hardness. What does that mean? Light is either bright or not right? The brightness of the light is more of a quantity of light discussion not a quality, this topic is covered in part one of my series on learning to see light here. For me, when I was learning lighting theory, I realized that light tends to operate differently than I expect it to. This is illustrated in the inverse square law which details light falloff as the distance of the light source from the subject is increased. This is explained in my previous article here. Light also differs in my expectation in the proximity of the light source from the subject and the type of shadow that is cast.
The softness of the light is generally indicative of the type of shadow that is cast on or by the subject when a light source is applied. To understand this softness and hardness theory, you must first understand the parts of the shadow. This illustration shows the three parts of the shadow, only two of which we will focus on in this article. The Umbra is the darkest part of the shadow and the Penumbra is the area between the Umbra and the lightest area. The sharpness, or definition of the Penumbra indicates the softness of the light source. How can you make a light source hard or soft, and how does this help me in my photography?
Like any art form, whether you like the sharp hard shadows, or the soft gradual ones, is up to you as the artist to decide what meets your vision for your image. The kind of light you use in your images also depends on photographic norms and whether you follow those norms. Hard contrast-heavy light is generally more suitable for athletes or hard-edged portraits while soft smooth shadows are usually more appropriate for formal portraiture. This is not to say that breaking the rules is not allowed, on the contrary some of my favorite portraits use harder edged light even when it would generally be seen as a soft light situation. Don’t think that this theory is only for strobes or studio portraiture. The idea here is to get you starting to look at the light and the way it interacts with the environment.
Here is the real crux of the idea, the softness of the shadows is determined by the size of your light source, and its proximity to your subject. In the case of portraiture, the softest light will be produced by a big light source like a softbox super close to your subject. Soft light will wrap smooth light shadows around your subject and are flattering to the face and other features. Conversely, a small light source far from your subject will provide sharp well defined shadows. An example of this would be shooting in the midday sun. This is why most people find landscape images shot in the middle of the day harsh and unpleasing. The light is cool (blue) and the shadows are sharp and well defined.
Illustration is the best way to demonstrate this, here are a couple images I made in Photoshop, using a white sphere lit by a single white point light source on a white background. First, look at the light on the sphere, its similar in both shots, however the big difference in the shots is the proximity of
the light source to the object. The intensity of the light is the same in both images. You should be able to see that the Umbra in the image with the light closer to the subject is less defined and the Penumbra is spread out and soft, creating a smooth transition from the Umbra to the fully lighted area. The second image however has a clearly defined Umbra, and a very sharp transition from Umbra to full light compared to the first image. For some reason, the fact that the light is softer the closer to the subject seems counterintuitive to me.
Diffusion and power of your light source also play a significant part in the softness equation. In my experience, the biggest impact on softness is achieved by adjusting the proximity and size of the light source to your subject.
Does this all make sense? I hope that this article serves as a starting point for further exploration for your lighting. As you travel through your world, notice the shadows, indoors and out. To reinforce this theory, consider this exercise, take a desk lamp or other light source and light a subject on a white background. Move the light closer and farther away, and pay close attention to how the shadows change in relation to the proximity of the light source to your subject.
Next week we will discuss the third aspect of light, color.
Get out there and take some pictures!