| 释义 |
Definition of f-number in English: f-numbernoun Photography The ratio of the focal length of a camera lens to the diameter of the aperture being used for a particular shot (e.g. f8, indicating that the focal length is eight times the diameter). 〔摄〕孔径焦距比，光圈数，f 值 Example sentencesExamples - All these f-numbers, focal lengths, film speeds and apertures are actually really simple to get to grips with once you understand how they relate to each other and to the finished picture.
- The configuration offers the advantage of high image quality, low distortion, and low f-number, making it ideal for spectral imaging.
- The f-numbers marked on a lens are only truly accurate when the lens is focused at infinity.
- The higher f-numbers mean the diameter of the lens can be smaller, so the lens, using only 20% to 25% as much material, will cost less and weigh less.
- So if you want to have that window frame, the couple, and the envelope all in focus, you need a narrow aperture, and so a large f-number, such as f22.
OriginEarly 20th century: from f (denoting the focal length) and number. Definition of f-number in US English: f-numbernounˈef ˌnəmbərˈɛf ˌnəmbər Photography The ratio of the focal length of a camera lens to the diameter of the aperture being used for a particular shot (e.g. f8, indicating that the focal length is eight times the diameter). 〔摄〕孔径焦距比，光圈数，f 值 Example sentencesExamples - All these f-numbers, focal lengths, film speeds and apertures are actually really simple to get to grips with once you understand how they relate to each other and to the finished picture.
- So if you want to have that window frame, the couple, and the envelope all in focus, you need a narrow aperture, and so a large f-number, such as f22.
- The f-numbers marked on a lens are only truly accurate when the lens is focused at infinity.
- The higher f-numbers mean the diameter of the lens can be smaller, so the lens, using only 20% to 25% as much material, will cost less and weigh less.
- The configuration offers the advantage of high image quality, low distortion, and low f-number, making it ideal for spectral imaging.
OriginEarly 20th century: from f (denoting the focal length) and number. |