in a continuous motion and thus simulates
the effect of movement of the camera
toward or away from the subject. However,
it does not actually move through space but
simply magnifies the image.Short-focal-length, long-focal-length, and middle-
focal-length lenses all have fixed focal lengths and
are known as prime lenses, but zoom lenses are in
their own category. Both prime and zoom lenses
have their specific optical qualities, and because
they are thought to produce sharper images, prime
lenses are generally used more than zoom lenses.
In the hands of an accomplished cinematographer,
the zoom lens can produce striking effects, but
when it is used indiscriminately, as it often is by
less skilled filmmakers, it not only feels artificial to
an audience but can unintentionally disorient view-
ers. As with all other aspects of cinematography,
the lens used must be appropriate for the story
being told.
Depth of fieldis a property of the lens that per-
mits the cinematographer to decide what planes,
or areas of the image, will be in focus. As a result,
depth of field helps create emphasis either on one
or more selected planes or figures or on the whole
image. The term depth of fieldrefers to the dis-
tances in front of a camera and its lens in which the
subjects are in apparent sharp focus. The short-
focal-length lens offers a nearly complete depth of
field, rendering almost all objects in the frame in
focus. The depth of field of the long-focal-length
lens is generally a very narrow range, and it leaves
the background and foreground of the in-focus
objects dramatically out of focus. In the middle-
focal-length lens, the depth of field keeps all sub-
jects in a “normal” sense of focus.
In virtually all shooting, cinematographers keep
the main subject of each shot in sharp focus to main-
tain clear spatial and perspectival relations within
frames. One option available to cinematographers,
however, is a rack focus(also known as select focus,
shift focus, or pull focus)—a change of the point of
focus from one subject to another. This technique
guides our attention to a new clearly focused point
of interest while blurring the previous subject in
the frame (see the illustration on page 247).
246 CHAPTER 6 CINEMATOGRAPHY
Zoom lensIn making The Hurt Locker(2008;
cinematographer: Barry Ackroyd), director Kathryn Bigelow
wanted viewers to experience the Iraq war as if they
were virtually involved in it. Thus, she had her camera team
use lightweight Super 16mm cameras that gave them the
mobility and flexibility to enter into the action and take
viewers with them. One of these cameras was fitted with
a zoom lens to allow its operator multiple perspectives on a
scene within one shot. Overall, the movie is concerned with
the highly dangerous work of a team that identifies and
disables enemy roadside bombs and similar incendiary
weapons. Here, the team, learning that a UN facility is
apparently in danger of some kind of attack, orders the
immediate evacuation of people from the building. In
this shot, the camera lens begins with an extreme long
shot [1] and then immediately shifts to a shorter focal
length to put us among the coalition soldiers leading the
frightened workers to safety [2]. The rapid, fluid movement
of the lens between a neutral observation point and
the people rushing toward the camera increases our
involvement with the military forces and workers. In
subsequent zoom lens shots, we see the weapons team
make surveillance of the immediate area, shoot a suspicious
man, and disarm a vehicle loaded with bombs, thus preventing
an explosion.21