22
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 signies 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 eects?
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.
55 mm F5.7 55 mm F22