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

• A modified first-derivative based QRST detection algorithm as well as a proposed adaptive f wave number detection algorithm was utilized in the method, and new conditions was set for AF detection.
  该方法应用了改进的一阶差分QRST检测算法和提出的自适应f波波数检测算法，并设置了新的房颤检测条件。
• 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 ray tracing method and vectorial Stratton Chu diffraction Integration are applied in the analysis of the imaging performance over the focal planes of hyperbolic lens and reverse microscope lens system with small F number.
  采用射线追迹结合StrattonChu矢量衍射积分公式的方法分析计算了小F数双曲透镜和倒置显微镜的焦面成像特性。
• F any product on which the serial number has been removed, defaced or modified.
  任何产品上的序列号已被删除，涂改或修改。
• This paper analyses colour subcarrier quantization noise in PCM coding of complete television singal. The relationship between quantization noise and sampling frequency ( f s) as well as quantizing bit number ( n) is discussed.
  分析了全电视信号PCM编码色度副载波量化噪声，并讨论了量化噪声与取样频率fs和量化比特数n的关系。
• Investigation on space optical system of high F number and high resolution
  大F数高分辨率空间望远镜光学系统
• 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。
• 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。
• 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 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。