stop down

Verb

stop down (third-person singular simple present stops down, present participle stopping down, simple past and past participle stopped down)

1. To decrease the aperture of a photographic lens, moving from an f/stop represented by a lower number to an f/stop represented by a higher number.
   • The f/stops are arranged so that as you stop down, each stop allows half the amount of light to pass through as the stop before it did.1982, Marvin J. Rosen, Introduction to photography: a self-directing approach, 2nd edition, →ISBN, page 71
   • To get an image with a larger “depth of field”—ie, where more of the distant objects as well as the nearer ones in a scene are in focus—the photographer must “stop down” the aperture of the lens, restricting the amount of light admitted.2002 December 12, “Images from a blurred world”, in The Economist, retrieved 03 Apr 2009