How many of us really appreciate the different qualities of light during the course of a single day. The reason you might not have noticed how light changes hour by hour is because the human eye is wonderfully adaptable continually compensating for varying conditions. But learn how to see the light, and respond to its changes, and your pictures will improve dramatically.
Colour of light
Natural light is made up of all the colors of the visible spectrum: red, orange, yellow, green, blue, indigo and violet. Each has a different wave length – short at the blue end of the spectrum, long at the red end. Mix all the colors and we get what we think of as white light. The Earth’s atmosphere contains air molecules that scatter light as it passes through them, and they scatter more light at the blue end of the spectrum than at the red end. That’s why the sky looks blue for most of the day.
As the sun sinks lower in the sky, its light is forced to pass through a lot more atmosphere than when the sun is overhead. So more of the short wave length blue part of the spectrum is scattered, leaving the long wave length red part to dominate. That’s why the sun looks red at sunrise and sunset.
The time shortly after sunrise and shortly before sunset is wonderful for all kinds of outdoor photography. These are known as the ‘golden hours’. During this time, sunlight is attractively softer as in its color, not its actual. Likewise, in the twilight hours when night recedes but before the sun has risen then again after sunset but before it is fully dark there comes another magical time. With the sun now below the horizon only the shorter blue wave lengths are scattered into the giving a blue-predominant, evenly diffused light. These are known as the ‘blue hours’.
So during the course of any sunny day, starting and ending with the darkness of night light changes color like this: black, blue, red, orange, yellow, white, yellow, orange red, blue, black.
Direction of light
When the sun is overhead in the middle of the day the light and the shadows are short. It is not usually accepted as a good time for photography although once you know the limitations it’s possible to exploit them for great pictures.
As the sun sinks lower in the sky its light becomes more directional and subjects are rendered differently depending on the direction from which light falls on them.
When the sun is behind the camera shining fully on the subject before you detail is revealed and crevice of a building, landscape, or even a human face. The result can be pleasing, but is rarely dramatic.
When light falls on the subject from an angle of, say, 30°-45° things start to improve. Shadows form in crevices, texture is revealed and your picture appears to acquire more depth. Pick a camera position when the light is shining at something like 90° to the subject and things become even more dramatic. Now one side of the subject might be brightly lit while the side facing the camera will fall into shadow. Subjects can be brightly lit against darker areas which really makes them stand out.
Go all the way and shoot when the sun is shining straight towards the camera and things change again. Light like this is across water where the sun’s sparkling reflections can form an integral part of the composition. Alternatively look for subjects with soft edges – a person’s hair or the coat of a sheep in a field, perhaps – and the sun will draw a halo of light around the subject’s profile. Translucent subjects like leaves flowers or the sails of boats lit from behind glow. More solid objects can be allowed to fall into darkness, producing striking silhouettes against the sun or a dramatic sky.