The nature of light

Article and Photography by Ron Bigelow

www.ronbigelow.com

It is very instructive to take note of what issues top photographers tend to write and talk about. For these are likely the issues that these photographers consider critical to their success. This being the case, the one topic that I see covered by top photographers, time and again, is the topic of light. The nature photographers often talk about seeking out certain light conditions or only shooting in specific types of light. The portrait specialists often discuss the lighting set ups and how it affects the final image. Even the photojournalists and travel photographers talk about trying to catch people in light conditions that best exemplify the people and the environments in which they live.
If light and its qualities are so important to top photographers, it would behoove us to examine light and understand its influence on our photography. Therefore, the purpose of this article is to look at light, its characteristics, and how it influences our images.

The Triple Nature of Light

Knowledgeable photographers will tell you that light has a triple nature for the photographer: color, direction, and quality. It is these characteristics of light that determine how our images turn out. It is an understanding and mastery of these characteristics that is often, at least partly, responsible for the best images that we see.

Color of Light

In 1665, Sir Isaac Newton was able to show, by using a double prism experiment, that ordinary, visible light is actually composed of seven colors (red, orange, yellow, green, blue, indigo, and violet). We now know that visible light is actually a continuous color distribution that starts with red light at the long wavelength end of the spectrum (wavelength has to do with the electromagnetic properties of light and refers to the distance from one crest of the electromagnetic wave to the next; if that doesn't make sense, don't worry about it) and ends with violet at the short end. In reality, visible light is only a portion of the light spectrum (light continues with infrared at one end of the spectrum and ultraviolet at the other).
Pure, white light is composed of a balance of these colors. However, light is not always pure. Often, the color balance of the light has been altered. Most frequently, this occurs because one or more of the colors have been, at least partially, filtered out of the light. When this happens, the color of the light changes. Because of this, the light that we experience is constantly changing color all day long and this affects the color balance of the images that we take. As covered in my article on advanced composition (Advanced Composition -- Part II) color affects the mood of an image. Consequently, the color of the light that illuminates a scene will impact the mood of the image and its ability to impart what the photographer wanted to communicate to the viewer of the final image. This works to great advantage for the knowledgeable photographer that uses her knowledge of light color to capture images where the color of the light is in harmony with the mood that the photographer wishes to create in the image. Conversely, the light often works to the detriment of the less knowledgeable photographer to contradict the mood that he intended to create or, at best, leaves him with an occasional, lucky image that impresses his friends but which he can not replicate due to his lack of understanding of the effect of the light on the emotional impact of the image.
Luckily, for photographers, we can simplify the color of light down to three basic categories of color: neutral light (no strong hue), warm light (tinted with yellow, orange, and red), and cool light (tinted with blue). We can simplify color down to these three categories because each of these categories has a different effect on how people respond to an image.

Figure 1: Neutral Light

Neutral light, which has no strong hue, is best used when a photographer wants the natural color of the objects to shine forth.
Figure 1 shows an image that was taken under fairly neutral light conditions. Under these conditions, the light did not add any significant colorcast to the image. This was desirable in this wave image. The white of the foam is critical to this image, and it was necessary to capture this white without any hue being introduced by the light. The use of neutral light allowed this to be done.
Neutral light is found away from both ends of the day (not in very early morning or in late afternoon). Light from a direct, overhead sun on a clear day may have a fairly neutral color. Photographers that wish to use neutral light need to beware of certain conditions. Heavy cloud cover will likely shift the color of the light toward blue. Also, shadows generally have a bluish tint. Light that is filtered or reflected in any way may pick up a hue. For instance, a photographer standing in a forest will likely find that the light has picked up a green hue from the leaves overhead. A photographer in a canyon with light reflected off the canyon walls will likely find that the light has picked up a color from the walls (probably a warm tone).
Warm light is good for creating inviting, dreamy moods in an image. People tend to associate warm light with feelings of comfort, friendship, and romance. The roaring fireplace that two lovers sit by casts a warm light on them. A husband and wife celebrating their anniversary eat dinner at a table illuminated by the warm, flickering light of a candle.

Figure 2: Warm Light

Figure 2 shows an image that was taken under conditions of warm light. At the time this image was taken, the sun had dropped low on the horizon and the light had developed a warm tone. This warm tone is most noticeable on the face of the cliff with the waterfall. The warm light gave the scene a gentle, enticing mood. The importance of the color of the light used to create this image can not be over emphasized. The waterfall in this image is the McWay Falls in Big Sur, CA. It is reported to be one of the most photographed waterfalls in the state. I have seen images of this waterfall from several professional photographers, and every single one of those images was taken in warm light conditions. In other words, for this and many other successful images, having the correct color of light is not something that is desirable; it is something that is mandatory.
Warm light is best found just after sunrise or just before sunset. This is because of the interaction of light and air molecules. Air molecules scatter the short wavelength blue light more than the long wavelength red light. Just after sunrise and before sunset, the sun is low on the horizon. This causes the sunlight to travel through more of the thicker air near the earth (the air gets thinner the higher one goes in the atmosphere). As a result, much of the blue part of the light is scattered. This leaves a warm light.
While the warmest light will generally occur within about a half hour of sunrise and sunset, the light can, sometimes, begin to pick up a warm tone a couple of hours before sunset (my experience has been that the light tends to lose its warm tone fairly quickly after the first half hour of sunlight in the morning). My experience is also that the late afternoon tends to produce warmer light than in the morning. Photographers that wish to use warm light need to watch out for clouds and shadows; both produce a bluish light.
Cool toned light is good for creating feelings of calm or cold. People tend to think of deep, calm lakes as being blue. A calm sky is usually blue. On the other hand, people also tend to associate blue with cold: ice may have a blue tint as well as the light of an early, winter morning.

Figure 3: Mixed Cool and Warm Light

Figure 3 illustrates the use of cool light. Actually, this image illustrates a mixture of light. The clouds low on the horizon display the very warm light of the last few rays of sunlight. However, the ocean has already fallen into the shadow of evening. The ocean is dimly lit by the sky above that has cast a cold, blue calm over the ocean. This contrast of light adds impact to the image. This image represents the dividing line of the day: the warm of the sun departing as the cold, ocean wind begins to chill the night air.
Cool light can often be found in the time between the first light of day and sunrise as well as between sunset and darkness. These twilight times often cast a soft, dim, bluish light over the terrain. Sometimes, a mixture of light is created at these times (as in Figure 3). Blue light can also be found under cloudy skies and in shadows.
Cool blue light is caused by the same phenomenon that causes warm light. Remember a few paragraphs back it was stated that the air molecules scatter the cool, blue light more than the warm, red light. This explained why the light just after sunrise and before sunset was warm, but what happened to all that blue light that was scattered? It was scattered into the sky. This is why the sky is blue. It is due to the scattering of the blue part of the light spectrum (this scattering happens all day long; it is just more pronounced during the very early and very late portions of the day).
During the twilight times, the sun is below the horizon. The landscape is illuminated by the sky alone. The light from the sky has a blue tint due to the scattered, blue light. This is also why the shadows are blue as they get most of their light from the sky rather than light directly from the sun.