There is not just one type of light in photography. Light has color and direction and it can be hard or soft. It is certainly not just about how bright the light is: the type of light determines the quality of a photo. And that quality can make or break your photos.
As a novice photographer who has not yet discovered everything that is possible with a camera, you already know a number of important things about light. For example, incandescent bulbs give a warm orange or yellow glow, and the light in the shade can be more bluish. Side light is soft and dimensional, and light from above is often harsh and distorting.
But to start thinking more about light, it is advisable to consider how you might break down the light in a given shot into its individual components.
The importance of the individual components
The problem with photography - and with any other art form on flat surfaces - is that it can be challenging to convey to your viewer that an image has three-dimensional depth. At first glance, it seems like the human brain should be able to make that interpretation quite easily - after all, we know that a photo of a tree is a photo of a tree, and a photo of a loaf is a photo of a loaf, etc.
But in practice this is not that simple. Visual cues are needed to tell us that the bread is not just a two-dimensional block that looks like a loaf.
There are many ways to make this clear. You can use leading lines, place objects in the foreground, play with depth of field..., but you can also simply use the light for this.
Good light has five values. It's not a requirement, but it may be very useful to understand why certain types of light can help add that sense of depth and dimension to an image that would otherwise look flat and two-dimensional. Those five values are responsible for creating the illusion that that two-dimensional object actually has texture, colour, size, shape and surface.
1. Highlights
This term is generally used to refer to that very bright spot of light that appears on a shiny object. When illuminated, a glass, plastic or metallic sphere will have a very bright highlight on its surface, which is essentially just a reflection of the light source.
This spot is important because it gives the viewer information about where the light source is and how reflective or shiny (or dull) the surface of the sphere is. This is the first visual cue you have to imagine a two-dimensional object being present in three dimensions.
Highlights are more visible on reflective objects such as metal or glass, where they are usually bright white. But that doesn't mean they aren't present on other objects - the highlights on dull surfaces are usually just lighter shades of whatever the color of that object is.
2. Diffuse light
The entire area of an object that is illuminated is not considered the highlights, because we generally refer to highlights as the brightest parts of an image. But technically, the rest of the object, that is, the part that is not in shadow, is also a highlight. This part of the object scatters the light that falls on it, and is therefore called diffuse light.
Diffuse highlights reveal an object's true color and texture. The highlights of a shot usually mask the details. When you have a photo of a person, part of that person's skin is in the shadows and part of it can be hidden by the highlights. The skin color that matches the actual skin color of the person in the image is the diffuse high light.
Diffuse highlights also show off an object's natural texture, revealing details of clothing, wrinkles, or other fine details.
3. The shadow area
This is one of the most important values of light to create that sense of dimension in a photo. The shaded side makes round objects look round. It is generally located opposite the light source, or in a position where no light can reach it.
It is darker than the diffused lights, and it can tend to overemphasize texture, i.e. make things look more textured than they actually are.
This can be a problem if your subject has spots or skin problems, as in the case of a portrait. What can also be interesting about this value of light is that it can contain the complementary color of whatever the main color of the object is. For example, a yellow ball has a dark side with a purple tint.
The transmission area
This is not technically one of those five values, but is important to consider because it is the area between the diffuse highlights and the shadows.
If your subject is lit in harsh light, there will be a fairly abrupt change between the diffuse highlights and the shadows, and very little of this transition area. If your subject is lit with soft light, you will get a more gradual transition between the two areas.
4. Reflective light
You may know this value as the light that bounces off in a shot to fill the shadows. This type of light is separate from the primary light source and can be used not only to fill dark areas, but also to add definition and shape to the subject.
...certain types of light can help add that sense of depth and dimension to an image...
5. Shadows
This is a different value from shadow area because it refers to the shadow cast by an object, rather than the shaded portion of that object. In general, an object needs some kind of shadow, because that shadow helps determine the object's place in its environment. It can also tell the viewer something about the texture of that environment.
For example, if an object is placed on a paved street, the shadow the object casts is determined by the shapes of the bricks. This is important to give an image some context and to anchor a subject in its environment.
Practice
Now take one of your most successful photos and see if you can see those five tonal values in it. You will probably find them there, because those five values in the light contribute a lot to the attractiveness of an image. Then look for some less successful images and look for these values there as well. Are any of those values missing?
Now put the above knowledge into practice. If you are photographing a subject that you can take your time with, consider whether you can find those five light values in the shot you are about to take. If not, experiment. Reflect the light in the shot with a reflector. Change position so that the specular highlight and shadow side are more prominent. Make sure that the object casts a shadow and that there is a smooth and gradual transition between the diffuse highlights and the shadow side. Learn to do this consciously, so that it can take place on a subconscious level every time you take photos.
