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What is depth of field? It simply means
the distance that provides clear and sharp photo after focus. When we
focus with a camera, there is a certain length of distance that is
clear and sharp. Any subject that falls into this length of distance
will be shown clearly in the photo whereas those subjects that are
outside this distance will be blurred. The further away from the
distance of clear view, the subject will be even blurred. In other
words, if the depth of field is shallow, then there is more chances
that a lot of subject in the photos will be blurred; whereas with very
deep depth of field, then most of the subject in the photos will be
clear and sharp to see.
We can control the depth of field according to situation and the photo
that we wish to take. Depth of field is mainly affected by the aperture
size, the focal length and the subject distance.
The bigger the aperture size, then the depth of field will be shallow.
With a big aperture, most of the object before and after the subject
focused will be blurred. With smaller aperture size however will give
us a large depth of field and most of the object before and after the
subject focused will remain clear and sharp.
The longer the focal length also will result the depth of field to be
shallow. Hence generally when using tele lens the depth of field will
be shallow whereas when using wide angle lens, the depth of field will
however be long.
The distance of the subject also affects the depth of field of a photo.
If the subject is closer, then the depth of field will be shallow.
Contrary, if the subject is far away, then the depth of field will be
increased.
Some cameras have a depth of field meter that with a press of button
will indicate the distance that is clear and sharp. This is useful when
taking photo with shallow depth of field, we would not want a photo
that has the eye is sharp and the nose is blurred, right? However, this
gives disadvantage when taking photo with small aperture. During small
aperture, the amount light going in is fewer and with the use of depth
of field meter, it will result the view to be darker when looking into
the viewfinder.
Generally, we use small aperture to take landscape photographs as in
order to get a clear picture of the scenery, we need a large depth of
field. However, small aperture also means that we need a longer shutter
speed to have a sufficient exposure. Hence for landscape photography,
we usually need to use tripod to stabilize.
For portraits photo, we usually uses shallow depth of field to bring
out the subjects in the photo. However, with shallow depth of field, we
need to be very careful in focusing as it can easily get out of focus
and result with a blurred photos.
Picture with large depth of field
Picture with small depth of field
Notice the difference between the two photos above. The one with the
large depth of field will show much more details on the tomatoes, the
skin texture, the warer drops. Whereas for the picture with small depth
of field, the details of the tomato is blurred and the appeareance of
the apple become much outstanding.
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