NIKONOS II - Depth of Field

22
EXPOSURE CONTROL
Depth of Field
Depth of field refers to a zone extending in front of and behind
the plane of sharpest focus. It extends a greater distance
behind the subject in focus than in front. Within this zone, blur
(or unsharpness of the image) is negligible and everything can
be accepted as being in sharp focus. Depth of field depends
on three factors: foca1 length of the lens, lens-to-subject
distance and taking aperture. The smaller the aperture and the
shorter the focal length of the lens, the greater the depth of
field (for example, wideangle lenses have more depth of field
than telephotos). Also, the closer the subject, the smaller the
depth of field. These three factors can operate independently
or in conjunction with one another and one factor may act to
partially cancel the effect of the others.
1. Lens at fuH aperture Small depth of field with only main subject in
focus.
2. Lens at smaHest aperture Great depth of field with suhject, background
and foreground in focus.