21
Concepts in Photography
Depth of eld
Portraits or still-life photos mostly acclaimed by people are the ones on
which the background is out of focus so the subject looks pronounced.
Depending on the focused areas, a photo can be blurred or sharpened.
This is called 'a low DOF' or 'a high DOF'.
The depth of eld is the focused area around the subject. Therefore, a
small DOF signies that the focused area is narrow and a large DOF means
the focused area is wide.
A photo with a small DOF, which stresses the subject and makes the rest
of it blurred, can be obtained by using a telescope lens or selecting a low
aperture value. Conversely, a photo with a large DOF which shows all the
elements on the photo sharply focused can be achieved by using a wide
angle lens or selecting a high aperture value.
Small Depth of Field Large Depth of Field

What controls out-of-focus eects?

DOF depends on aperture value

The wider the aperture is (namely the lower the aperture value), the lower
the DOF becomes. Under the condition where the focal length is equal, a
low aperture value leads to a photo with a low DOF.
50 mm F5.7 50 mm F22