f/stop

Noun

f-stop (plural f-stops)

1. Any of the discrete steps or stopping points for adjusting the aperture of a lens, either marked on a ring on the lens and adjusted by rotating that ring or marked in the display of a digital camera and adjusted by buttons or touch-sensitive controls.
   • Before you know what f-stop you want, you first have to know what it is you are trying to accomplish in the photograph: Do I want to freeze action, or show motion, and consider shutter speed, or, do I need to get a cast of people in focus, or focus selectively, and cater to aperture?2006, Michael Grecco, Lighting and the Dramatic Portrait, Amphoto Books, →ISBN, page 22