Understanding "Light" is key to exercising creative control in your photography. One simple element of light is direction, it can have a dramatic effect on how a subject looks. The following four images are the same subject, Val's beautiful garden flowers, photographed with the same equipment and one light source. The difference is just in the position of that light.
Direction of light on the subject is always determined from the photographer point of view. This example is "Underlight." In nature things are not usually underlight, you often see this choice of lighting when you want to make something look unusual or spooky. Think about holding a flashlight under your face to achieve a ghoulish look at Halloween.
Indirect Backlight - The one light source was directed onto the wall in behind the flowers. This created backlight which turned everything into a silhouette. Imagine photographing someone standing in front of a big bright window.
Sidelight - This is often an attractive choice as it can create long shadows and help reveal texture. It's one of the reasons landscape images shot early morning or late in the day can look so beautiful.
Direct Backlight - In this last example the light is placed directly behind the subject. Imagine shooting in the direction of the sun at sunrise or sunset. Any subject that's translucent will glow from the backlight, here the flowers petals. Subjects that are fuzzy become rim light with strong backlight, imagine a fuzzy kitten or the velvet on elk antlers. Here the dangling strands of Amaranthus.
There is much more to understanding light than just these few examples. One other ingredient is how much light you choose to let in during the "Exposure." Which will be the topic of tomorrows post.