**f-number** — (f/#) A number used to indicate the size and light passing ability of the lens opening on most adjustable cameras. Common f numbers are f/2, f/2.8, f/4, f/5.6,f/8, f/11, f/16, and f/22. The larger the f number, the smaller the lens opening.… … Forensic science glossary

**f-number** — [ef′num΄bər] n. Photog. a number that represents the relative aperture of a lens, equal to the focal length divided by the effective diameter of the lens aperture: a higher number indicates a smaller opening … English World dictionary

**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

**f-number** — n. Photog. the ratio of the focal length to the effective diameter of a lens (e.g. f5, indicating that the focal length is five times the diameter). Etymology: f (denoting focal length) + NUMBER * * * ˈf number 7 [f number f numbers] noun a… … Useful english dictionary

**f-number** — /ef num beuhr/, n. Optics, Photog. a number corresponding to the ratio of the focal length to the diameter of a lens system, esp. a camera lens. In f/ 1.4, 1.4 is the f number and signifies that the focal length of the lens is 1.4 times as great… … Universalium

**f number** — noun the ratio of the focal length to the diameter of a (camera) lens system • Syn: ↑focal ratio, ↑stop number, ↑speed • Hypernyms: ↑ratio * * * f number, Photography. the focal length of a lens divided by its effective diameter. An f/4 lens is… … Useful english dictionary

**f-number** — WikiV (F Stop also known as f number or f system) The speed or ability of a lens to pass light. It is calculated by dividing the focal length of the lens by its diameter. The f stop also is a factor in more areas of focus in the image known as… … Audio and video glossary

**f number** — /ˈɛf nʌmbə/ (say ef numbuh) noun the ratio of the focal length of a lens system to its effective diameter, used to number aperture openings in a camera. Also, f stop. {f(ocal length) + number} … Australian English dictionary

**f-number** — [[t]ˈɛfˌnʌm bər[/t]] n. opt pht a number corresponding to the ratio of the focal length to the diameter of a lens system, esp. a camera lens Symbol: f • Etymology: 1890–95 … From formal English to slang

**f number** — see f ratio … Dictionary of units of measurement