Definitions for "F-stop"
Keywords:  aperture, iris, focal, lens, halves
The calibration on the lens indicating the aperture (the opening in the lens' iris). The larger f-stop number, the smaller the aperture; the smaller the f-stop number, the larger the aperture.
Common term used to define lens aperture setting (the ratio of focal length divided by diameter of aperture)
A number that indicates the relative size of the opening of the lens (aperture) and written, for example, as f/16. Because the number is obtained by dividing the focal length of a lens by it's effective aperture, the larger the aperture, the smaller the f-number. In the conventional series, each number represents an aperture that admits half as much light as the preceding one. Thus f/16 lets half as much light as a lens opened to f/11.
Keywords:  exposure, see
See exposure