- focal length ratio
- 焦距比
English-Chinese dictionary of mechanical engineering (英汉机械工程大词典). 2013.
focal length ratio
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Focal length — The focal length of an optical system is a measure of how strongly it converges (focuses) or diverges (diffuses) light. A system with a shorter focal length has greater optical power than one with a long focal length. Thin lens approximation For… … Wikipedia
35 mm equivalent focal length — In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term originates from the time when the vast majority of photography was done … Wikipedia
focal ratio — noun the ratio of the focal length to the diameter of a (camera) lens system • Syn: ↑f number, ↑stop number, ↑speed • Hypernyms: ↑ratio * * * noun : f number … Useful english dictionary
Matthiessen's ratio — For the electron mobility rule, see Matthiessen s rule. In optics, Matthiessen s ratio is the ratio between the distance from the centre of the lens to the objective, versus the lens radius[1]. This is of particular importance in fish, where the… … Wikipedia
f ratio — or f number or f stop (f/ or f) a measure of the light gathering power of the lenses in cameras and telescopes. The f ratio, for example f/4 or f4, is the aperture of the lens (the effective diameter of the lens, which may be reduced or… … Dictionary of units of measurement
F-ratio (disambiguation) — F ratio or f ratio may refer to:* f number, f ratio, or focal ratio, the ratio of the focal length of an optical system to the diameter of its entrance pupil; * f ratio, in oceanography, which relates recycled and total primary production in the… … Wikipedia
zoom ratio — TV Range of a lens focal length, from most zoomed in field of view to most zoomed out. Expressed as ratio: 6:1, for example, implies that the same lens from the same distance can make the same image appear six times closer. [See focal length,… … Audio and video glossary
Infrared Space Observatory — Infobox Space Telescope name = Infrared Space Observatory background = caption = organization = European Space Agency (ESA) major contractors = Aerospatiale (currently Thales) alt names = nssdc id = 1995 062A location = In decaying orbit orbit… … Wikipedia
Depth of field — The area within the depth of field appears sharp, while the areas in front of and beyond the depth of field appear blurry … Wikipedia
F-number — In optics, the f number (sometimes called focal ratio, f ratio, or relative aperture [Smith, Warren Modern Lens Design 2005 McGraw Hill] ) of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; … Wikipedia
Crop factor — The outer, red box displays what a 24×36 mm sensor would see, the inner, blue box displays what a 15×23 mm sensor would see. (The actual image circle of most lenses designed for 35 mm SLR format would extend further beyond the red box than shown… … Wikipedia
