slr.jpg (29959 bytes)


Photography Class
Bong S. Eliab
First Semester
Humanities Division
School of Arts and Sciences
Ateneo de Davao University

Syllabus | NotesPapers | Projects

the area or 'zone' of a photograph,
from front to back,
which is in focus



Little depth of field

ltldof.jpg (18486 bytes)


Greater depth of field
More sharp detail is visible.

dof3.jpg (12199 bytes)

eastrbun.jpg (28915 bytes)


Three factors can affect the depth of field:
  • focal length of the lens
  • distance from the camera to the subject
  • the size of the aperture or the setting of the f-stop

I. Focal length of the lens

The depth of field is inversely proportional to the focal length of the lens; that is, the smaller the focal length number of the lens, the greater the depth of field. For example, a 28mm lens has the ability to capture more of the picture in sharp focus than a 100mm lens.


II. Distance from the camera to the subject

Depth of field is directly proportional to distance; i.e. a subject at a greater distance will have greater depth of field than a close-up subject. Therefore, you need not worry as much about a distant subject being out of focus.


III. The size of the aperture or (f-stop)

While changing the aperture (f-stop) will not have a striking effect on the depth of field for a distant subject or a wide angle (short focal length) lens, it can make a great deal of difference in a close-up or a photo taken using a telephoto or zoom lens.

A wider aperture (smaller f-stop number) will result in a shallower depth of field. You can use this to keep either the foreground or background out of focus while maintaining the subject in focus. When changing the aperture setting, you will need to also adjust the shutter to maintain the correct exposure.

Aperture = F5.6
Shutter = 1/1000
Little/Shallow depth of field
Aperture = F22
Shutter = 1/60
Greater/More depth of field
dof1.jpg (10716 bytes) dof3.jpg (12199 bytes)


While most photographers take the above factors into account and make adjustments based on experience, or bracket their exposures, it is possible to calculate depth of field using mathematical formulas. If you would like to explore this topic further, check out these sites:



Syllabus | NotesPapers | Projects


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Ateneo de Davao University
13 December 2002