What is aperture?

  • (noun): A natural opening in something.
    See also — Additional definitions below

Aperture

In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time).

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Some articles on aperture:

Aperture - In Scanning or Sampling
... The terms scanning aperture and sampling aperture are often used to refer to the opening through which an image is sampled, or scanned, for example in a Drum scanner, an image ... The sampling aperture can be a literal optical aperture, that is, a small opening in space, or it can be a time-domain aperture for sampling a signal waveform ... density fluctuations as seen through a 0.048 mm sampling aperture ...
Aperture Foundation
... The Aperture Foundation was founded in 1952 by Ansel Adams, Minor White, Barbara Morgan, Dorothea Lange, Nancy Newhall, Beaumont Newhall, Ernest Louie, Melton ... The first issue of Aperture (magazine) was published in spring 1952 in San Francisco ... Aperture's efforts increased respect for photography and its popularity among contemporary artists soared ...
Selenium Meter - Types of Meters - Coupled Meters
... sophisticated cameras have the match-needle instrument coupled directly to aperture and shutter speed setting rings on the lens tube instead to a separate ... were even used for setting exposure settings directly, mainly for automatic aperture setting ... trap-needle" pressing the shutter release mechanically gripped the meter needle, then moved an aperture control up to hit the needle, setting the aperture to a value controlled ...
Lenses For SLR And DSLR Cameras - Aperture and Depth of Field
... The aperture of a lens is the opening that regulates the amount of light that passes through the lens ... The relative aperture is specified as an f-number, the ratio of the lens focal length to its effective aperture diameter ... A small f-number like f/2.0 indicates a large aperture (more light passes through), while a large f-number like f/22 indicates a small aperture (little light passes through) ...
Synthetically Thinned Aperture Radar
... Synthetic Thinned Aperture Radiometry (STAR) is a method of radar in which the coherent product (correlation) of the signal from pairs of antennas is measured at different antenna-pair spacings (ba ... Furthermore, aperture thinning reduces the overall volume and mass of the antenna system ... the image due to a decrease in signal-to-noise for each measurement compared to a filled aperture ...

More definitions of "aperture":

  • (noun): A device that controls amount of light admitted.
  • (noun): An man-made opening; usually small.

Famous quotes containing the word aperture:

    Animals used to provide a lowlife way to kill and get away with it, as they do still, but, more intriguingly, for some people they are an aperture through which wounds drain. The scapegoat of olden times, driven off for the bystanders’ sins, has become a tender thing, a running injury. There, running away ... is me: hurt it and you are hurting me.
    Edward Hoagland (b. 1932)