Excerpt from Chapter 1 - All about light

Simplicity Is Essential

Great lighting is simple and most accomplished photographers will agree that lighting should not call attention to itself. Even if you are adept at using five lights in harmony, the impact of the subject is still more important than the impact of the lighting. Often, an elegant photograph can actually be made with a single light and reflector—and nothing more. Ultimately, simplicity in your lighting technique creates greater control over how the light shapes the subject and produces subtle effects, rather than exaggerated ones.

That simplicity is an underlying principle of successful lighting is hardly surprising. In nature, on this planet at least, life revolves around a single sun—so there is only one true light source. As a result, we are subconsciously troubled by the disparity we perceive when multiple shadows, created by different light sources, contradict each other. If, on the other hand, there is a single unifying direction to the light, with a single set of corresponding shadows, we are satisfied that it appears normal.

Natural daylight is elegant and soft. Near the edge of a clearing, David Beckstead positioned his bride so that the shade would backlight her, making her veil transparent and dreamlike. Learning to see light is the first step in attaining images that exhibit great lighting technique.

Light is Energy
Light is energy that travels in waves, which are traveling energy. Waves usually move through a medium, like water. Imagine the waves in a swimming pool after someone has jumped in. Is it the water that is moving or something else?

Actually, the water in the pool stays pretty much stationary. Instead, it is the energy, the wave, caused by the person jumping into the pool that is moving. Light waves are different than water waves, however, in that they don’t require a medium through which to travel. In fact, light travels most efficiently in a vacuum—other elements like air and water actually slow light down. Light travels so fast in a vacuum—186,000 miles per second—that it is the fastest known phenomenon in the universe!

Light waves consist of both electric and magnetic fields of energy, known as electromagnetic fields. Like all forms of electromagnetic energy, the size of a light wave is measured in wavelengths—the distance between two corresponding points on successive waves. The visible spectrum is only a tiny section of the full range of the electromagnetic spectrum, which also includes radio, microwaves, infrared, ultraviolet, X-rays, and gamma rays—types of waves that are differentiated by their unique wavelengths. The wavelengths of visible light range from 400–700 nanometers (one millionth of a millimeter).

Photons
Without delving into a lengthy description of physics, it is sufficient to say that photons are the raw material of light. When we see visible light, we are witnessing countless numbers of photons moving through space as electromagnetic waves. Photons are produced by light sources and reflected off objects. On an atomic level, light works like this: an atom of material has electrons orbiting its nucleus. Different materials have different numbers of electrons orbiting their individual atoms. When atoms are excited or energized, usually by heat, for example, the orbiting electrons actually change to a different orbit and then gradually revert. This process emits photons, which are visible light having a specific wavelength or color. If there are enough photons and the frequency is within the visible spectrum, our eyes perceive the energy as light and we see. Any system that produces light—whether it’s a household lamp or a firefly—does it by energizing atoms in some way.

What is White Light?
When we look at a visible light source, it appears to be colorless or white. Of course it is not white. Instead, it is a mixture of colors that the eye perceives as white. We know this because if you shine “white” light through a prism, you get a rainbow of colors, which are the individual components of the visible spectrum.

The color of daylight is not white, it’s anything but white, depending on the time of day. Here, David Beckstead used the very low-angle, late-in-the-day light of sunset to capture his bride in hues of red and gold. As the sun nears horizon, it takes on a peculiar quality, almost like a stage spotlight.

The Characteristics of Light’s Behavior
Unless it is traveling though a vacuum, the medium through which it travels alters how light behaves. Four different things can happen to light waves when they traverse a medium: the waves can be reflected or scattered; they can be absorbed (which usually results in the creation of heat but not light); they can be refracted (bent and passed through the material); or they can be transmitted with no effect. More than one of these results can happen at the same time with the same medium. What’s important to know is that what will happen is predictable. This is the key to understanding how lighting works in a photographic environment.

Once the sun passes below the horizon, it’s brilliant rays are reflected off of the sky and atmosphere, creating a huge, natural overhead softbox. This image was made by Bruce Dorn of his daughter Carly, on her wedding day.

Reflection.
One of the characteristics of light that is important to photography has to do with reflected light waves. When light hits a reflective surface at an angle (imagine sunlight hitting a mirror), the results are totally predictable. The reflected wave will always comes off the flat, reflective surface at the same angle at which the incoming wave of light struck the surface. In simple terms, the law can be restated as this: the angle of incidence is equal to the angle of reflection. Whether you are trying to eliminate the white glare of wet streets as seen through the viewfinder or to minimize a hot spot on the forehead of your bride, this simple rule will keep you pointed toward the source of the problem.

This rule also has applications in product and commercial photography. For example, when lighting a highly reflective object like silverware, knowing that the angle of incidence equals the angle of reflection tells you that direct illumination will not be the best solution. Instead, you should try to light the surface that will be reflected back onto the shiny object’s surface.

Daylight streaming in through a window or balcony is soft, yet directional. In this image, Marcus Bell harnesses the soft light of a balcony and the reflected soft light from the white wall against which the bride is leaning. Because the wall’s surface is irregular, it scatters the light in all directions, unlike a polished reflector, which would redirect most of the light falling on it. The effect here is like photographing the bride with an ultra-diffused studio softbox.

Scattering.
Scattering is reflection, but off a rough surface. Basically, because the surface is uneven, incoming light waves get reflected at many different angles. When a photographer uses a reflector, it is essentially to distort the light in this way, reflecting it unevenly (or, put another way, so that it diffuses the light).

Translucent surfaces, such as the rip-stop nylon used in photographic umbrellas and softboxes, transmit some of the light and scatter some of it. This is why these diffusion-lighting devices are always less intense than raw, undiffused light. Some of the energy of the light waves is being discarded by scattering, and the waves that are transmitted strike the subject at many different angles, which is the reason the light is seen as diffused.

Refraction. When light waves move at an angle between materials, they change both speed and direction. Moving from air to glass (to a denser medium), for example, causes light to slow down. Light waves that strike the glass at an angle will also change direction, otherwise known as refraction. Knowing the degree to which certain glass elements will bend light (known as the refractive index) allows optical engineers to design extremely high-quality lenses, capable of focusing a high-resolution image onto a flat plane (the film or image sensor). In such complicated formulas, now almost exclusively designed by computers, the air surfaces between glass elements are just as important to the optical formula of the lens as the glass surfaces and their shapes.

Daylight scattered by passing through thick cloud cover and then again by ground-hugging fog renders subjects with a strangely beautiful transparency. This marvelous shot was done by Jo Gram of Flax Studios in Christchurch, New Zealand on a very foggy wedding day. Jo made the image with a Canon EOS 1D Mark II and 70–200mm f/2.8 lens. The only effect she introduced was some vignetting in RAW file processing.

In lighting devices, refraction is used with spotlights and spots with Fresnel lenses. These lenses, placed close to the light source, gather and focus the light into a condensed beam that is more intense and useful over a greater distance than an unfocused light of the same intensity. Spotlights are theatrical in nature, allowing the players on stage to be lit from above or the side by intense but distant lights, but they also have many applications in contemporary photography.

Absorption.
When light is neither reflected nor transmitted through a medium, it is absorbed. Absorption usually results in the production of heat but not light. Black flock or velvet backgrounds are often used to create dense black backgrounds because they absorb all of the light striking their surfaces.

Light can be made diffuse when it passes through a translucent medium, such as rip-stop nylon, the material used in softboxes and umbrellas. Light can also be softened when it bounces off of an irregular surface, such as a stucco wall. The image in a lens can also be softened by a soft focus lens, or in this case with a special lens called a Lensbaby, with which you can physically alter the plane of focus. Instead of the focus plane being parallel to the film plane, the lens adjusts laterally and diagonally to shift the focus plane. This wonderful cake (called “devacake” by the photographer) was photographed by Cherie Steinberg Coté with a Lensbaby and a Nikon D100 camera. Cherie shifted the lens to the left to produce a very shallow band of focus.