Canon EOS 1 V HS - Manual (Page 123)

Basic Photography Terms
This is the range where acceptable focus can be achieved in front of and
behind the point of optimum focus. The smaller the aperture (the larger the
f-number), the deeper the depth of field. And the larger the aperture (the
smaller the f-number), the shallower the depth of field.
The depth of field is affected as described below:
(1) A smaller aperture (a larger f-number) increases the depth of field.
For example, stopping down to f/8 obtains a greater depth of field than
f/4.5.
(2) A lens with a shorter focal length increases the depth of field.
A wide-angle lens obtains a deeper depth of field than a telephoto lens.
(3) A longer distance between the camera and subject increases the depth
of field.
(4) The depth of field behind the point of optimum focus is longer than the
depth of field in front of the point of optimum focus.
----------------- Depth of field
Point of optimum focus
1
Aperture set to f/2. Aperture set to f/22.
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