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
Effects of diaphragm opening on depth of field.