Depth of Field

Depth of Field (DOF) is generally what is going to differentiate between you and a professional photographer.

Technically, DOF = how deep is your focus. Meaning to us, objects how far apart are in focus? For example, if your subject is standing in front of a far off mountain and your subject and mountain both are in focus then you have a "deep" DOF. If only the subject or only the mountain is in focus then you have a "shallow" DOF.

In any photo, only one focal plane is sharp. The area of sharpness is also 1/3rd in front of and 2/3rd behind the focal plane. So, if you have a person standing 10 feet away and that person is in focus then you may have 2 feet before him and 4 feet behind him in reasonably sharp focus.

Most dramatic effects are achieved by a shallow DOF. However, for specific cases (such as a subject in front of the mountain and you want the mountain and the subject both in focus) you can choose deep DOF.

DOF is controlled by 3 aspects:
- Aperture (small=deep, large=shallow; remember: small=big f stop, large=small f stop)
- Distance between you and subject, subject and other objects
- Focal Length (Wide Angle=Deep; Telephoto=Shallow; remember: Wide=Small Focal Length; Telephoto=Large Focal Length)

However, since both distance and Focal length are constrained by physical measures generally, Aperture is your true friend. Also, Aperture changes DOF without changing composition and hence is also more useful.


FactorShallow DOFDeep DOF
ApertureWide (1.4f, 2f, 2.8f)Narrow (8f, 11f, 16f, 22f...)
Focal LengthTelephotoWide Angle