Aperture, ContinuedAperturesettingsAperture settings (f/stops) regulate the intensity of light allowed to strike thefilm surface. The aperture control ring on the lens barrel is marked in aseries of f/stops that relate to the openings of the iris diaphragm.F/stopscontrol overall image sharpness, depth of field, and partially correct lensaberrations. Adjacent numbers in the series of f/stops admit light in aproportion of 2 to 1.For example, changing aperture setting from f/5.6 tof/8 changes the amount of light by decreasing the light by half, a procedurecalled stopping down. Changing from f/5.6 to f/4 doubles the light. Thischange is called opening up. When the diaphragm is set to its smallestnumerical aperture, it is said to be wide open. The larger the f/stop numbers,the smaller the opening and the less light admitted.Figure 7-16 illustrates the differences between f/stop openings.Figure 7-16.—Aperture: A. Aperture ring; B.Aperture openings at various f/stops.Continued on next page7-26
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