Canon EOS 600 - Manual (Page 58)

DEPTH OF FIELD
When your subject is in focus, there is a certain
area in front of it and behind itwhich will also be in
focus This range of sharpness is called “depth of
field”
Depth of field has the following characteristics:
1) The smaller the aperture, the wider the depth
of field and vice versa
2) The shorter the lens focal length is, the greater
the deptf^ of field, provided that aperture and
shooting distance are the same
3) The farther the shooting distance, the greater
the depth of field
4) Depth of field is generally greater in the back­
ground than the foreground.