This requires a suspension of disbelief but it helps make the system explainable

A 3:1 ratio was achieved outdoors by using a small reflector to raise the shadow level—and by having the child look up into the overhead shade, illuminating the recesses of the face, like the eye sockets. Stacy Bratton, a well known children's portrait artist, made this image with a wide-open aperture to diminish overall sharpness. Note the beautiful hair light provided by the soft overhead lighting.

in themselves a ratio between the size ofthe lens aperture and the focal length of the lens, which is why they are expressed as "f/2.8," for example. The difference between one f-stop and the next full f-stop is either half the light or double the light. For example f/8 lets in twice as much light through a lens as f/11 and half as much light as f/5.6. However, when we talk about lighting ratios, each full stop is equal to two units of light, each half stop is equal to one unit of light, and each quarter stop is equivalent to half a unit of light. This requires a suspension of disbelief, but it helps make the system explainable and repeatable.

In lighting of all types, from those made in sunlight to those made in the studio, the fill light is calculated as one unit of light, because it strikes both the highlight and shadow sides of the face. The amount of light from the key light, which strikes only the highlight side of the face, is added to that number. For example, imagine you are photo- graphing a small family group and the key light is one stop (two units) greater than the fill light (one unit). The one unit of the fill is added to the two units of the key light, yielding a 3:1 ratio; three units of light fall on the highlight sides of the face, while only one unit falls on the shadow sides.

left—In this elegant portrait by Anthony Cava, the man's rugged good looks cried out for a dramatic 5:1 lighting ratio. The ratio was controlled by increasing the distance of the subject from the light source. The farther he is from the window light, the more focused and contrasty the light becomes.

facing page—In traditional terms, one might say this lighting lacks drama. However, in contemporary circles—and more importantly, to the brides who cherish such images—very soft lighting is perfect and very editorial. In this image by Becker, the lighting ratio is about as close to 1:1 as you can get. The image is very soft with very little differentiation between shadow and highlight values. Yet, notice the exquisite detail in the gown. The only near-black tones are created in the vignette, by the photographer in Photoshop.

Lighting Ratios and Their Unique Personalities. A 2:1 ratio is the lowest lighting ratio you should employ. It reveals only minimal roundness in the face and is most desirable for high-key effects. High-key portraits are those with low lighting ratios, light tones, and usually a light or white background (see page 33). In a 2:1 lighting ratio, the key and fill-light sources are the same intensity (one unit of light falls on the shadow and highlight sides of the face from the fill light, while one unit of light falls on the highlight side of the face from the key light—1+1:1=2:1). A 2:1 ratio will widen a narrow face and provide a flat rendering that lacks dimension.

A 3:1 lighting ratio is produced when the key light is one stop greater in intensity than the fill light (one unit of light falls on both sides of the face from the fill light, and two units of light fall on the highlight side of the face from the key light—2+1:1=3:1). This ratio is the most preferred for color and black & white because it will yield an exposure with excellent shadow and highlight detail. It shows good roundness in the face and is ideal for rendering average-shaped faces.

A 4:1 ratio (the key light is 11/2 stops greater in intensity than the fill light—2+1 + 1:1=4:1) is used when the photographer wants a slimming or dramatic effect. In a 4:1 ratio, the shadow side of the face loses its slight glow and the accent of the portrait becomes the highlights. Ratios of 4:1 and higher are considered appropriate for low-key portraits, which are characterized by a higher lighting ratio, dark tones, and usually a dark background (for more on low-key portraits, see page 35).

A 5:1 ratio (the key light is two stops greater than the fill light— 2+2+1:1=5:1) is considered almost a high-contrast rendition. It is ideal for adding a dramatic effect to your subject and is often used in character stud-

■ SCENE CONTRAST

Lighting ratios determine contrast and to what degree the light will slim the subject's face. The higher the lighting ratio (the greater the tonal difference between highlight and shadow sides of the face will be), the thinner the subject's face will appear. The ratio is also an indication of how much shadow detail you will have in the final portrait. A desirable ratio for color film or digital is 3:1, which is flattering to the average face and provides plenty of shadow detail.

ies. Shadow detail is minimal with ratios of 5:1 and higher. As a result, they are not recommended unless your only concern is highlight detail.

Seasoned photographers are able recognize the very subtle differences between lighting ratios, so fractional ratios (produced by reducing or increasing the fill light amount in quarter-stop increments) are also used. For instance, a photographer might recognize that with a given face, a 2:1 ratio does not provide enough roundness and a 3:1 ratio produces too dramatic a rendering, thus he or she would strive for something in between—a 2.5:1 ratio.

0 0

Post a comment