Canon EOS 10D - Manual (Page 162)

162
Basic Terminology
1 2
Depth of field
This is the range where acceptable focus can be achieved in front of and behind the point of
focus. The smaller the aperture (the higher the f/number), the deeper the depth of field. And
the larger the aperture (the lower the f/number), the shallower the depth of field.
The depth of field is affected as described below:
(1) A smaller aperture (a higher f/number) increases the depth of field.
For example, stopping down to f/8 obtains a deeper 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 (2) is longer than the depth of field in
front of the point of optimum focus (1).
Exposure
Exposure occurs when the image sensor is exposed to light. Correct exposure is obtained
when the image sensor is exposed to a proper amount of light in accordance with its sensitivity
to light. The correct exposure is adjusted with the camera's shutter speed and aperture.
Depth of field
Point of optimum focus
Aperture set to f/22. Aperture set to f/2.