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Light in Photography -   LIGHTING -

When used in portrait photography, the term “Key” refers to the overall tone of the final photograph. The elements of the portrait that play into the tone of it are the color of the background, the color of clothing used and the color of any props or foreground elements. Portraits that have a consistent key generally have much more of an impact that those whose elements are not consistent. It is true as well that, though rare, tones can be mixed in a photo with success. A danger in mixing tones is that the potential for confusion on the part of the viewer.

Generally, portraits are classified in one of three keys – low key, middle key or high key. Low key portraits are created using a dark background and dark clothing and props. You can identify the key of a portrait by determining the average tone for the scene.

Generally a low key portrait would have more dark elements than bright ones. Clothing and background might be black or dark browns giving the feeling of drama or rigidity. Low key portraits may also be shot with a higher lighting ratio near 3:1 as contrast is acceptable due to the drama of a lower tone.

A high key portrait setup would involve the use of a white or off white background and brighter clothing. A high key portrait can be challenging as it requires a great deal of light control and has the most risk of overexposure and loss of detail. In general they would have a low lighting ratio near 2:1. A common background for high key portraits is paper which is slightly overexposed resulting in a pure white seamless background and a feeling of cleanliness. Great care is usually taken to separate the subject from the background to eliminate shadows. These portraits also tend to require more light and thus more power and lighting equipment to create.

As expected, a photo which has tones in the middle of high and low would be called a middle key portrait. Often middle key portraits will use skin tone to set the mood. In these cases, clothing may be used to accent the tone of the skin with contrast rather than allow all elements to blend together. Often a high key portrait can be converted to a middle key portrait by reducing exposure.

Often the background sets the tone for the image and as such key should be a consideration at the beginning of a portrait setup. A background should not take focus off of the subject, but rather help lead the eye to the subject in the final image. Take time to identify your overall tone, or key before you arrange the lighting setup and you will be surprised at the results.

Low-key lighting is a style of lighting for film or television. It attempts to create a chiaroscuro effect. In traditional lighting design for black and white photography, also called three-point lighting, there are a key light, a fill light, and a back light.

Low key light shows the contours of an object by throwing areas into light or shadow while the fill light provides partial illumination in the shadow areas to prevent a distracting contrast between bright and dark. For dramatic effects, one may wish the contrast to be high — to emphasize the brightness of the sun in a desert scene, to make a face look rugged, seamed, and old, or to isolate details in a mass of surrounding shadow. A variety of methods can be used to create these effects.

The key to fill ratio, as measured using an instrument to measure light intensity, e.g., a light meter, is the ratio of the intensity of the key light to the fill light. Low key lighting actually has a much higher ratio, e.g. 8:1, than does high key lighting, which can approach 1:1.

It is perfectly possible to use fill light in these large areas of shadow, reducing the contrast. Generally the term 'low key' refers to cases in which no such care is taken.

Low key is also used in cinematography to refer to any scene with a high contrast ratio, especially if there is more dark area than light. Compare with high-key lighting.

Mood lighting is a term used to describe the use of light to illuminate an object or background in a deliberate manner to evoke a certain mood or emotion. This highly skilled lighting technique is very subtle but nevertheless can achieve highly effective outcomes. An example of this is an evil character deliberately illuminated from beneath the chin giving them a certain eerie and demonic appearance.

Ambient lighting refers to the overall illumination of an environment without the addition of lighting for photography. This includes practical lamps, overhead fluorescent, sunlight or any previously existing light.


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