Depth
of Field
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Depth
of field refers to how much is in focus in front of and behind the subject
that is focused upon. “More” depth of field means that more is in focus.
“Shallow” depth of field means that very little is in focus other than the
subject. The photographer focuses
specifically on one object or part of an object. Anything behind or in front
of that focusing point will be less in focus. The farther away an object is
from that focusing point, the less in focus it will be. Step
I is to decide on the
main focusing point. Step 2 is to
decide how much depth of field is desired to achieve the desired “look” of
the photograph. Step 3 is to set
the camera’s aperture or choose an appropriate lens or focal length. The
human eye cannot determine what is truly sharp, inch by inch, in a scenic
landscape. Yet, one inch in a close-up of a flower easily shows which petal
is sharp and which is blurry. One
way the photographer controls the amount of depth of field is by changing the
camera’s aperture setting. A small aperture such as f/l6 has a larger depth
of field than a large aperture like f/3.5. A picture taken with f/l6 will
have more area in focus in front of and behind the point focused upon. A
picture with f/3.5 results in shallow depth of field with one area being
obviously the sharpest. Another
way to control the apparent depth of field is with the choice of lens or
focal length. A wide angle lens has larger depth of field than a telephoto
lens. A landscape taken with a wide angle lens will put more area in focus
when used with a small aperture. If the photographer stands on the same spot
and uses a telephoto lens, there will be less apparent depth of field in the
picture, especially with a large aperture. It is a combination of aperture
and lens that affect the depth of field. In
cameras with “Portrait Mode” the beginning photographer needs to know that
the camera is automatically setting a large aperture for shallow depth of
field (which will blur the background and foreground). “Landscape Mode”
automatically sets the camera to a small aperture in order to put as much as
possible into focus. Source of information -
from articles from the PSA Journal (Photographic Society of |