stop

Definition: (1) Noun: Step or unit of change in exposure. * Camera controls are arranged so that (a) a doubling or halving of shutter time equals a stop increase or decrease in exposure e.g. 1/700sec to 1/350sec or to 1/1400sec; (b) a change by a factor of square root of 2, or approximately 1.414X, in the lens' working aperture equals a change in exposure of a stop e.g. f/4 to f/2.8 or to f/5.6. (2) Adjective: ~ bath: Acidic bath used to arrest development of e.g. silver-based materials. * Usually a dilute solution of an acetic acid is used: if an indicator dye is use, known as indicator stop bath. Verb: (3) To arrest the action of a processing e.g. development. (4) To arrest or abort a computer action or process. * This usually requires the issue of a specific command e.g. pressing Control + X, or Command + '.' (period).

Previous Term: stock  Next Term: storage media