f number

英 [ˈef nʌmbə(r)]

美 [ˈef nʌmbər]

焦距值；光圈数

英英释义

noun

• the ratio of the focal length to the diameter of a (camera) lens system
  Synonym:focal ratiostop numberspeed

双语例句

• The effective focal length and back working distance of the system are respectively 100 mm and 113 mm, while the F number is 2.0.The system which has only three lenses contains two negative germanium lenses and one positive zinc selenide lens.
  该系统全视场为14°，有效焦距为100mm，后工作距为113mm，F/2.0.系统采用锗和硒化锌两种材料，为三片镜结构。
• Based on the hydraulically and thermally developing flows, the flow and temperature fields, Nu, f and field synergy number Fc are obtained for different Re and wall temperatures.
  模拟以通道入口段的流动和换热为对象，得到了不同Re和不同壁温下的流场和温度场，对流换热的Nu和阻力系数，以及场协同数Fc。
• The optical performance of small F number diffractive microlens arrays little voice
  小F数衍射微透镜阵列光学性能研究
• The degree of a face f in G ( written r ( f)) is the number of edges of G incident with f, each cut edges counting as two edges.
  一个面所关联的边的个数（割边要计算两次），被称为面的度，用r（f）表示。
• A computing method of f he number of lateral sides and the coordinates of vertices of a mixture CONVEX-POLYHEDRON having lower and upper bounds
  兼有上、下界约束混料凸多面体的面数与顶点坐标的一种计算方法
• Methods Testing patients 'pronunciation with of without complete denture and contrast with normal speech sounds. Using USSA to analyes its frequency and parameter number of wave crest ( F) and energy number ( P).
  方法对无牙颌患者戴全口义齿前、后与正常对照组进行语音a/i/u的检测并对其共振峰参数频率值（F）、能量值（P）的USSA语音频谱的分析。
• The matric characteristics and convergences on F-number space
  F数空间的度量特征及收敛性
• The results show that under increasing pressure the band occupation numbers change, with s and p electron number gradually transferring to d and f electron number.
  结果表明，随着压强的增加，能带电子占据数发生变化，s分波和P分波电荷逐步向d分波和f分波电荷转移；电声矩阵元中p（？）
• You can really think of it as the sum of the values of f everywhere divided by the number of points everywhere.
  可以认为这是所有点处f值的和，再除以所有点的数。
• The F number standard for concrete floor developed by american concrete Institute and Canadian Standards Association is superior to the standard known as the gep under a straight edge. This paper briefly introduces its significance and application metod on site.
  介绍了美国混凝土学会和加拿大标准学会的F数标准，以及使用该混凝土地面平整度和水平度标准的现实意义和现场测量方法。