Monday, April 16, 2007

Brief Glossary of Photography Terms

Some of the material on this site may use terms that are unfamiliar to those new to photography lingo. The glossary below may help, I'll keep it updated as I see terms that should be on this page. For more detail, follow the Wikipedia links or check out one of these more comprehesive glossaries:

  • 100% Crop: This means the image is shown pixel per pixel on your monitor. A 200% crop means each image pixel takes four pixels (two horizontal, two vertical) on your screen.
  • Chromatic Aberration: a lens problem where different colors of light bend travel through the lens slightly differently and cause purple or cyan halos around edges of high contrast. Mostly a problem for cheaper lenses.
  • Composition: The placement or arrangement of the elements of a photo. Composition is really hard to define, but it is essential a measure of how interesting the picture is, on the whole. Often, composition is more of a function of the shapes, colors, and intensity of an image than the subject itself. While composition is relatively subjective, most people will often agree if an image is well-composed or not.
  • DSLR (or dSLR): SLR camera which uses a digital microchip sensor instead of film.
  • Film Speed: The sensitivity of film to light, where lower values are less sensitive, require longer exposure times, yet have less grain (noise). Typically measured in terms of ISO, such as 100 ISO is a pretty slow daylight film with small grain (low noise). A 400 ISO film is useful indoors because it requires 1/4 of the light to generate an exposure, but has more grain. Digital cameras also use the ISO linear scale to electronically control the tradeoff between sensitivity and noise of the imaging chip.
  • Focal length: An optical specification (usually in millimeters) of a lens reflecting how much of the scene the lens can render on the sensor. For 35mm cameras, 50mm is a normal lens (approximating the eye), 35mm or less is a wide-angle lens, and 80mm or more is a telephoto lens. On digital cameras with a sensor smaller than 35mm size (such as the Digital Rebel series, 20D, and 30D) you need to adjust the true focal length to get the 35mm equivalent. For most Canon cameras with smaller sensors, this multiplier is 1.6.
  • Glass: Slang, meaning lenses and optical equipment.
  • Grey-market: Something (usually electronic equipment) bought overseas and then shipped to the USA. Usually identical to the USA version but the manufacturer won't honor the USA warranty for a grey-market item.
  • ISO: See film speed.
  • Saturation: The purity of a color. For instance, a bright, pure red is highly saturated while a pastel red has low saturation.
  • Shutter Speed: The amount of time the film (or digital sensor) is exposed to light from the scene. Typically measured in fractions of a second.
  • SLR: Single-Lens Reflex. A type of camera which uses a single lens for both the viewfinder and taking the pictures, so what you see is what you get (mostly). The reflex refers to the use of a moving mirror to allow dual use of the lens.
  • Soft: When referring to an image, it means the image is not sharp and out of focus. When referring to lenses, soft means the lens produces unsharp images even when focused well.
  • Vignetting: a lens problem where the corners of the image are darker than the center.
  • Wide-open: A maximum-size aperture setting (for the 50mm f/1.8, an aperature of f/1.8 is wide open).

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