Icon class icon_class fas fa-quote-left icon_class_computed fas fa-quote-left Related content The Newtonian telescope has flat secondary mirror and a paraboloid or spherical primary mirror Source Wikipedia Copyright information Text from Wikipedia and Wiktionary web pages quoted for educational purposes is subject to the Wikipedia Creative Commons Attribution ShareAlike Licence Snippet kind INFO Keywords optics f-number f-ratio f-stop focal length Previous snippet Full quote In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture"). It is also known as the focal ratio, f-ratio, or f-stop URL https://en.wikipedia.org/wiki/F-number Next snippet Related snippets Related snippets (backlinks) Visit also Visit also (backlinks) Flags
