Canon EOS Rebel xsi - Manual (Page 73)

73
f : Changing the Depth of Field
When using a high aperture, note that camera shake can occur
in low light scenes.
A higher aperture will make the shutter speed slower. Under low
light, the shutter speed can be as long as 30 sec. In such cases,
increase the ISO speed and hold the camera steady or use a tripod.
The depth of field depends not only on the aperture, but also
the lens and subject distance.
Since wide-angle lenses have a wide depth of field, you need not set
a high aperture to obtain a sharp picture from the foreground to the
background. On the other hand, a telephoto lens has a narrow depth
of field.
And the closer the subject, the narrower the depth of field. A farther
subject will have a wider depth of field.
Set the aperture so that the shutter speed display does not
blink in the viewfinder.
If you press the shutter button halfway and change
the aperture while the shutter speed is displayed,
the shutter speed display will also change to
maintain the same exposure (amount of light
reaching the image sensor). If you exceed the
adjustable shutter speed range, the shutter speed
display will blink to indicate that the standard
exposure cannot be obtained.
If the picture will be too dark, the 30" (30 sec.) shutter speed display
will blink. If this happens, turn the <6> dial to the left to set a lower
aperture or increase the ISO speed.
If the picture will be too bright, the 4000 (1/4000 sec.) shutter speed
display will blink. If this happens, turn the <6> dial to the right to
set a higher aperture or decrease the ISO speed.
Shooting Tips
H73_04.fm Page 73 Monday, November 12, 2007 3:35 PM