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focal length |
Also found in: Dictionary/thesaurus, Medical, Wikipedia, Hutchinson | 0.02 sec. |
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focal length, distance the distance from the focal point of a lens or mirror to the reflecting surface of the mirror or the centre point of the lens focal length [′fō·kəl ‚leŋkth] (optics) The distance from the focal point of a lens or curved mirror to the principal point; for a thin lens it is approximately the distance from the focal point to the lens. Also known as focal distance. Focal length A measure of the collecting or diverging power of a lens or an optical system. Focal length, usually designated f ′ in formulas, is measured by the distance of the focal point (the point where the image of a parallel entering bundle of light rays is formed) from the lens, or more exactly by the distance from the principal point to the focal point. See Geometrical optics The power of a lens system is equal to n′/f ′, where n′ is the refractive index in the image space (n′ is usually equal to unity). A lens of zero power is said to be afocal. Telescopes are afocal lens systems. See Diopter, Lens (optics), Telescope How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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| Longer focal lengths compress information, while wide-angle lenses can create a richly layered sense of depth. Made up of 8 pieces instead of the first generation's 11, the design reduces complexity and the number of components, replaces separate LEDs on the pillar with an acrylic light pipe that can be tuned for different focal lengths, and will be capable of combining LEDs to produce amber light as well as red for a combined stop/turn function. It took both [visual and scientific evidence] to make a compelling argument" For instance, Falco used the sizes of objects and people in the paintings to calculate diameters, focal lengths, and other characteristics of lenses and mirrors that might have been used to project those forms. |
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