This scene of a sailboat adrift on an azure sea off Curaçao’s coast is filled with light tones and contrasting dark values in just the right proportion to reinforce the high-key mood.

    Mixed together in appropriate proportions, the quality and quantity of light can imbue the subject with one more characteristic: namely, mood. Lighting that is bright and airy—or cheerful, if you will—may impart those attributes to the subject it embraces. When the lighting is muted, the subject may take on a more sullen and brooding appearance.
    We can take the concept of mood one step further by defining it as low-key or high-key. A low-key mood is subdued and is dominated by darker and deeper tonalities: namely, black and gray values. A high-key mood is elevated, dominated by lighter tones and brighter colors, perhaps evoking a sense of ethereal fantasy. Having said that, the image may be high-key yet evoke mystery and foreboding, as in a fog-enshrouded scene.
    Owing to the prevalence of bright tones and colors in our daily lives, it is much easier to unintentionally underexpose than overexpose a scene. Granted, today’s camera metering systems do a better job of getting it right more often than not, but they aren’t foolproof. And they certainly can’t read your intentions. So, when you purposefully want to retain the light values and bright colors in a scene for a high-key effect, you often have to make a conscious effort to do so.
    Still, we can take that high-key effect up a notch—through controlled overexposure. In the process, we strive to avoid the loss of critical detail by preventing these important highlights from burning out. A contrasting dark tonality might benefit the picture, provided it’s not overwhelming. While less popular these days, soft focus (via lens or filter) will spread the highlights and enhance the high-key effect, again bordering on ethereal. Interestingly, it can also be used to make low-key exposures more pronounced. A fog or diffusion filter might also do the trick. Even sheer white gauze can elevate the mood, and a sheer black stocking can help tone it down, with either held over the lens.
    Low-key effects are, in my view, more difficult to create than high-key ones. Add a contrite facial expression or a stooped posture and the mood becomes downcast or even forlorn. (If you have trouble seeing a color image as low-key, revisit it after converting the photograph to black and white—a simpler task, admittedly, with digital imaging.)
    You can further enhance the low-key effect through controlled underexposure—and the key word here, again, is controlled. In contrast to exposing for a silhouette (when you still want part of the scene—the background—correctly exposed), in this instance you may not want any part of the scene to appear properly exposed. However, at the same time, you don’t want to create the impression that the image is underexposed or that the underexposure was unintentional. You have to draw a fine line. It’s very subjective. The thing to avoid is a muddied and muddled look, with a loss of critical detail, in which the message behind the photograph is lost.
    In the final analysis, the mood is defined more by your own mind and personal associations than by your will in imbuing the subject with certain qualities. Sometimes the image is high-key or low-key simply by virtue of the predominant tones and nothing else. The image may evoke no mood at all. The subject itself plays the defining role in any mood you associate with the picture.

A professional photographer himself, John Neubart has been writing about all aspect of photography for more than twenty-five years. He is the author of Amphoto's Studio Lighting Solutions, among other books, and his popular column, "Technically Speaking," appears regularly in Photo District News. His book is available from Watson-Guptill Publications as well as other retailers.