Zone focusing is a technique for working fast without focusing on each shot. You set the lens to manual focus at a chosen distance and use a fairly small aperture, such as f/8 or f/11. Everything within a certain range, or zone, will then be acceptably sharp.
Street photographers often use it, because they can shoot quickly when something happens. A depth of field scale on the lens shows the zone of sharpness. If your lens has no scale, a depth of field app or chart can tell you the range for your focal length, aperture and distance. See also hyperfocal distance.
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