<P> For a given subject framing and camera position , the DOF is controlled by the lens aperture diameter , which is usually specified as the f - number , the ratio of lens focal length to aperture diameter . Reducing the aperture diameter ( increasing the f - number ) increases the DOF because the circle of confusion is shrunk directly and indirectly by reducing the light hitting the outside of the lens which is focused to a different point than light hitting the inside of the lens due to spherical aberration caused by the construction of the lens ; however , it also reduces the amount of light transmitted , and increases diffraction , placing a practical limit on the extent to which DOF can be increased by reducing the aperture diameter . </P>
<P> For a given subject framing and camera position , the DOF is controlled by the lens aperture diameter , which is usually specified as the f - number , the ratio of lens focal length to aperture diameter . Reducing the aperture diameter ( increasing the f - number ) increases the DOF because the circle of confusion is shrunk directly and indirectly by reducing the light hitting the outside of the lens which is focused to a different point than light hitting the inside of the lens due to spherical aberration caused by the construction of the lens ; however , it also reduces the amount of light transmitted , and increases diffraction , placing a practical limit on the extent to which DOF can be increased by reducing the aperture diameter . </P>
to control depth of field and amount of light what should be adjusted
to control depth of field and amount of light what should be adjusted
the lens aperture diameter
the lens aperture diameter