A blurred photograph results when movement of
the subject or camera during exposure causes a
shift in the position of the image on film.
The shutter speed required to "freeze" an
object's action normally increases as the object's
speed increases; however, no matter what the
speed, an object moving across the viewfinder field
requires a faster shutter speed than one moving at
the same speed directly toward or away from the
camera. Similarly, a moving object near the camera
(or one appearing nearer due to use of a longer-
focal-length lens or a close-up accessory) requires a
faster shutter speed than one farther away.
Blur from camera motion depends on such
factors as the lens being used, the apparent
closeness of the subject when viewed through the
lens, the shutter speed, and the camera-support
method. Since longer-focal-length lenses and close-
up accessories increase the relative size of the
subject, even a slight movement of the camera will
be magnified on film; the greater weight and size of
such lenses and accessories may also make it
difficult to hold them steady. A good rule to
follow is that the slowest shutter speed that can be
safely used by most people when hand-holding a
lens is the reciprocal of the focal length. For
example, for a 125mm lens, the speed would be
1/125 sec; for a 300mm lens, it would be 1/500
(1/300 raised to the next faster speed to be on the
safe side).
Use of a sufficiently fast shutter speed is also
important when taking pictures from a moving,
vibrating vehicle such as a boat, car, train, or plane
(especially to prevent blurring the foreground, if
any) or from a vibrating object such as a bridge. To
reduce transmission of the vibrations through your
body to the camera, relax your body and avoid
direct contact with the object as far as possible.
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BLUB FBOM CAMERA/SUBJECT MOVEMENT
