EZLighting Guide: Nature of Light

by Clive Dexter| Photographer at Large

The nature of light in the angle of incidence.

At EZbackgrounds we are embarking on a new project for our members and readers. We will be studying every aspect of light as it relates to photography with an emphasis on portrait lighting.

We are going to take our time and explore a little bit at a time to allow for better retention of information and experimentation with the principles and projects put forth.

This article will article will answer questions relating to the behavior of light. As much as you might want to jump into lighting setups right away, the knowledge of how light works will yield far more benefits when you are able to "see" the light.

Seeing the Light

Light travels in waves, much like ripples in a pond when you throw a rock into the water.

Light travels in waves like waves in a pond.

These waves can be large or small depending on factors including the size of a particular light source. When we use the term “wavelength”, it is referring to the size and frequency of a light wave.

The full range of wavelengths from the shortest and the longest is called the electromagnetic spectrum. Inside that span of wavelengths is the spectrum of visible light, which is what we can see with our eyes.

The electromagnetic spectrum with visible spectrum with nake eye.

The full range of visible light is exactly the same as they appear in a rainbow; violet, indigo, blue, green, yellow, orange and red.

Predicting the Angle of Light Reflection

Unlike the ripples in a pond that only travel visibly across the surface of the water, light travels in all directions from its source like an ever-expanding bubble.

If the waves encounter an obstacle straight-on, they will bounce off that obstacle and reverse course, traveling in the opposite direction.

If the waves encounter an obstacle at an angle, they will bounce off in a direction like a billiard ball would on a pool table.

There is a moderately complex mathematical formula for this, but the only thing you need concern yourself with is the concept.

You can take a flashlight and point it at the mirror to see how the light behaves in a completely predictable way.

However, most surfaces are not completely flat. You may think of the walls in your home as being flat and smooth, but it is likely that they actually have a small amount of texture. These tiny irregularities in the texture have their own angles of incidence which combine with all the other irregularities. The result is called diffusion.

Angle of incidence on an uneven surface.

Diffusion is another critical concept to understand. Since the light is being reflected at multiple angles, one could say it has a blurring effect. This creates what we could call a “soft” light, while a directly projected light would be seen as “harsh” or “hard” lighting.

Big and Soft or Small and Hard

Simply put, hard light is where the transition between highlights and shadows is sudden and distinct. Think mid-day when it’s sunny outside. Hard light makes for great shadow puppets, but is rarely good for portraiture.

Soft light has a more gradual transition or gradient between the highlights and shadows. Much like the shadows on a cloudy day, you may barely be able to tell the difference between the shadow and the highlight within the softest of light.

A main principle of lighting states that the bigger the light source in relation to the subject, the softer the light. On the other hand, the smaller the light source, the harder the light cast. This is a key concept to understand.

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