c. Depth of field also increases as the lens opening or aperture is
decreased, because the size of each cone of light decreases in proportion to
the aperture. The top and center sections of figure 2-24 show that a lens with
a large aperture reproduces sharply only those objects located between B and D.
In the lower sections, the sharpness range of the depth of field is increased
to the distance of A to E, because the lens diaphragm has been closed down to a
smaller aperture.
Figure 2-24.
Effects of diaphragm opening on depth of field.
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