Canon EOS 30 - Page 91

Reference
Depth of field
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.
(2) A longer distance between the camera and subject increases the depth
of field.
(3) When subject distance remains the same, a lens with a shorter focal
length 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.
Aperture set to f/2. Aperture set to f/22.
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