Light sources are natural, artificial or some combination of both. Natural lighting sources include the sun and the moon. An artificial light source is man-made. Known as strobe lighting, this type of light source illuminates subjects with concentrated or broad areas of light. An example of one popular artificial light source, built into lots of cameras, is a flash unit. The mixing of natural and artificial light sources can influence the quality of light that falls on a subject.
Artists and photographers manipulate light quality in a number of ways. They mix light sources, absorb light with dark materials and bounce light off reflective surfaces. Manipulation of a subject's light quality produces even, hard or soft lighting. Hard lighting results in a high-contrast image with hard edges. Soft lighting produces lower-contrast images with softer edges. Some photographers use light in ways that create a full range of tones and capture lots of intricate detail.
Lighting creates dramatic or subtle transitions between an image's darkest and lightest areas. High-contrast images come from strong lighting conditions, like direct sunlight. A high-contrast image will lack tonality between the subject's highlights and shadows. Low-contrast images are often the result of diffused, soft lighting situations.
Photographers often measure a subject's light with a light meter. Doing so allows them to adjust the lighting until it's right. Some natural-lighting photographers will wait until the subject shows a perfect amount of contrast before they take a picture.
Great master painters like Rembrandt used special lighting conditions in creating signature styles. The term "Rembrandt lighting" is a common portrait photography technique. Other well-known lighting styles include broad lighting, short lighting, and butterfly lighting. Many lighting techniques depend on a main light for controlling how light falls on a subject. These techniques often require adjusting a light's height or distance from the subject.
You can learn more about lighting by studying one of the most amazing styles in art history. The Chiaroscuro style uses light in ways that produce large amounts of volume and dimension within compositions. Chiaroscuro influences the look of many famous films, paintings and photographs. The men who made this dramatic approach to lighting famous include Botticelli, Velazquez, Vermeer, Raphael, Caravaggio and Rubens.