An important concept to understand when dealing with studio lighting for portrait photography is contrast. Contrast is the difference in the amount of light that falls on the dark areas of a scene and the amount of light that falls on the highlight areas of a scene. Humans can see a wide range of contrast while film and digital capture devices are much more limited in the light level ranges that they can record. For this reason, we must use caution when lighting a scene, and consider the ratio of the amount of light between light and dark areas or the Lighting Ratio.
Due to the latitude of film and digital sensors, it is the photographer’s goal to find the exposure that strikes the appropriate balance between the highlights and shadows. You must begin by deciding the desired “feel” of the final image. If you wish to obscure shadow detail and draw attention to the subject, high contrast lighting may be most appropriate. On the other hand, you may wish to show detail in both the highlight and shadow areas which would require lower contrast lighting. Once you know the effect you wish to obtain, you can begin to identify the proper lighting ratio for the shoot.
