The Digital Photography Companion

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EXTEND THE DYNAMIC RANGE OF YOUR IMAGE

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Extend the Dynamic Range of Your Image

Cameras don’t see the world as we do. Our eyes (connected to our supercomputer

brains) can pick out the shadow detail of a shaded tree trunk and the subtleties in a

bright sky at the same time. Your typical digital camera can’t. At the root of this discrep-

ancy is something called dynamic range, the ratio of the lightest to the darkest point

in the scene. On a bright day, our optical system can easily see 50,000 subtle variations

in tone. A typical 8-bit photo captured by your camera picks up a mere 256 variations.

Considering these limitations, it’s a wonder our pictures turn out as well as they do.

To compensate for this difference in dynamic range, photographers sometimes shoot

through a graduated density filter, a piece of glass which darkens the sky (typically the

brightest part of a photo) in hopes of compressing the scene’s tonal values so that the

camera can record them all in one exposure.

Traditional Approach: Graduated Filters

Graduated density filters work great when you have a simple bright area, such as a sky,

with a clean horizontal line. e filter itself is dark at the top, usually a neutral gray, and

it then gradually gets lighter toward the bottom. e thinking is that you position the

dark area of the filter over the bright sky, bringing its ...