Monday, March 26, 2007
Digital Photography Glossary
Check out common terms you need to know for digital imaging
Labels: Learning Center
Depth of Field
The degree to which the scene remains in acceptably or perceived sharp focus in front of and beyond the focal plane. A larger aperture number (i.e., f/16) produces a broader depth of field. A smaller aperture number (i.e., f/2.8) can be used to throw the background out of focus, drawing the viewer's eye to the main subject.
A simulated zoom effect that enlarges the image on a portion of the image sensor. Akin to cropping, fewer pixels are used to capture the image, and although you end up with a closer view of the subject, the final image is generally of significantly lower resolution With lower resolution, the ability to enlarge the photo without affecting image quality is reduced.
The range of tones, from lightest to darkest, that can be recorded, displayed or reproduced by devices such as image sensors, scanners, printers and monitors. The term is also used to describe the light-sensitivity range of film and the range of reflected light of a print. A photograph produced by a camera with high dynamic range, for example, will retain image detail in both the shadows and highlights.
Pixels on the sensor actually used to capture an image. Often, not all the pixels on a sensor can be used because: 1) some pixels on the surrounding edges of a sensor are masked off to determine a black point; or 2) some cameras, especially compact ones, have lenses that are unable to cover the entire sensor area. The difference between actual and effective pixels is usually minimal, i.e., a 5.2-megapixel camera, for example, will provide 5.0 effective megapixels.
A controlled amount of light projected to an image sensor or frame of film. This determines the lightness or darkness of an image and can be controlled manually by the photographer or automatically by the camera or by a combination of the two. If the aperture is too large and/or the shutter speed too slow, an image will be too light, i.e., overexposed and vice versa. (See also Metering.)
The degree to which light from a scene is magnified by a lens. A short focal length, such as 28mm, will have a wider angle of view compared to the tight or telephoto focal length of a large 300mm lens. Zoom lenses have the ability to move through a range of focal lengths, while prime lenses are fixed at a specific focal length.
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