22Concepts in PhotographyDepth of fieldPortraits or still-life photos mostly acclaimed by people are the ones onwhich 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 field is the focused area around the subject. Therefore, asmall DOF signifies that the focused area is narrow and a large DOF meansthe focused area is wide.A photo with a small DOF, which stresses the subject and makes the restof it blurred, can be obtained by using a telescope lens or selecting a lowaperture value. Conversely, a photo with a large DOF which shows all theelements on the photo sharply focused can be achieved by using a wideangle lens or selecting a high aperture value.Small Depth of Field Large Depth of FieldWhat controls out-of-focus effects?DOF depends on aperture valueThe wider the aperture is (namely the lower the aperture value), the lowerthe DOF becomes. Under the condition where the focal length is equal, alow aperture value leads to a photo with a low DOF.55 mm F5.7 55 mm F22
