Natural light photographers have no direct control over the position of their principal light source, and must live with this limitation. Nevertheless, the position of the sun changes on an hourly and seasonal basis and consequently offers a wide range of photographic opportunities. Sometimes it is possible to choose a time of day to work, and hence select the angle of the light. Landscape photographers do this all the time. Otherwise, the subject and viewpoint may have to be moved relative to the sun.
Light falling directly onto a front-lit subject is uniform and produces very little in the way of highlights or shadows. Form is destroyed, texture is subordinated and the image becomes rather flat and dull. The illusion of depth in a two-dimensional image arises in part from changes in the amount of light reflected from the subject, and the consequent tonal variations. In the absence of this structural information an image is unlikely to be interesting.
Side-lighting is most effective for emphasizing form and texture in portraits, and when combined with a low sun angle offers some of the finest photographic opportunities. Wonderful effects can be captured in the hour following sunrise and the period just before sunset. However, direct light falling on the face can also produce unwelcome shadows around the nose and chin, and may leave eyes underexposed.
Back-lighting often produces the most dramatic effects. It outlines some subjects with attractive highlights and renders others incandescent, but some features may also be plunged into deep shadow. Such lighting is difficult to handle because a bright background has a significant effect upon an averaged exposure measurement. The subject may be grossly underexposed or even reduced to a silhouette. The solution is to reduce contrast by directing additional light into the shadows, take spot measurements from shadow areas and perhaps let detail in the bright background burn out.