f-number

基本解释

The matric characteristics and convergences on F-number space are investigated.
探讨了F数空间的度量特征及几种收敛性的关系。
When shooting, use a high F-number, this will help to blur the background and focus on the water.
拍摄过程中选用大光圈，这能模糊背景，从而关注水。
The aperture size (area of the aperture) of a lens could be calculated from focal length and the correspondent f-number.
光圈孔的大小，可从镜头的焦距与焦距比数中计算出来。

Without an adequate number of F-22s, U.S. pilots could have a tough time matching the performance of their Chinese counterparts in a future struggle for control of the Pacific.
FORBES: Inside Pentagon, Growing Alarm Over China's Military Prowess
An end-of-year report by Finnish software security company F-Secure highlights the growing number of hackers targeting Apple systems with malicious software, some of which could allow cybercriminals to steal security passwords.
FORBES: Apples For The Army
Although the number of F-22 fighters was capped at 187, the Air Force would increase its long-range strike capabilities by 50 percent and the penetrating component of long-range strike by a factor of five by 2025.
CENTERFORSECURITYPOLICY: Center for Security Policy

the numerical value of the relative aperture. If the relative aperture is f8, 8 is the f-number and indicates that the focal length of the lens is 8 times the size of the lens aperture &rarrsee alsoT-number