Deep focus is a photographic and cinematographic technique using a large
depth of field. Depth of field is the front-to-back range of focus in an image
— that is, how much of it appears sharp and clear. Consequently, in deep focus
the foreground, middle-ground and background are all in focus. This can be
achieved through use of the hyperfocal distance of the camera lens.
Deep focus is achieved with large amounts of light and small aperture. It
is also possible to achieve the illusion of deep focus with optical tricks or by
compositing two pictures together. It is the aperture of a camera lens that
determines the depth of field. Wide angle lenses also make a larger portion
of the image appear sharp. The aperture of a camera determines how much light
enters through the lens, so achieving deep focus requires a bright scene or
long exposure. Aperture is measured in f-stops with a higher value indicating a
smaller aperture. The opposite of deep focus is shallow
focus, in which only one plane of the image is in focus.
In the cinema Orson Welles and his cinematographer Gregg Toland were most
responsible for popularizing deep focus. Deep focus and deep space
When deep focus is used, filmmakers often combine it with deep space. Deep
space is a part of mise-en-scene, placing significant actors and props in
different planes of the picture. Directors and cinematographers often use
deep space without using deep focus, being either an artistic choice or
because they don't have resources to create a deep focus look, or both.
Directors may use deep focus in only some scenes or even just some shots.
Other auteurs choose to use it consistently throughout the movie,
either as a stylistic choice or because they believe it represents reality
better. Directors like Stanley Kubrick, Kenji Mizoguchi, Orson Welles and Jean
Renoir all used deep focus as part of their signature style.
Deep focus and different formats The choice of shooting format affects
how easy it would be to achieve a deep focus look. This is because the size of
the sensor or film gauge dictates what particular lens focal length would be
used in order to achieve a desired viewing angle. Smaller sensors or film
gauges will require an overall range of shorter focal lengths to achieve any
desired viewing angle than larger sensors or film gauges. Because depth of
field is a characteristic of lens focal length, it is easier to achieve a
deep-focus look with a smaller imaging sensor or film gauge. For example: a
40mm lens will give a 30-degree horizontal angle of view in the Super35
format. To achieve the same viewing angle with a 1/2" 16:9 sensor, you would
need a 13mm lens. A 13mm lens inherently has much more depth-of-field than a 40mm
lens. To achieve the same depth of field with a 40mm lens would require a very
small aperture, which in turn would require far more light, and therefore
time and expense. Some filmmakers make deliberate use of
the deep focus capabilities of digital formats. Miami Vice is among the many
big budget movies that have been shot digitally in recent years.
Cinematographer Dion Beebe had this to say:
We also decided that there were attributes of HD technology we liked and
wanted to exploit, like the increased depth of field. Because of the cameras'
chip size, they have excessive depth of field that we decided not to fight, but
rather utilize. Split-focus diopter
In the 70s, directors made frequent use of the split-focus diopter. With this
invention it was possible to have one plane in focus in one part of the
picture and a different plane in focus in the other half of the picture. This
was and still is very useful for the anamorphic widescreen format, which has
more depth of field. A split diopter is half convex glass
that attaches in front of the camera's main lens to make half the lens
nearsighted. The lens can focus on a plane in the background and the diopter
on a foreground. A split diopter does not create real deep focus, only the
illusion of this. What distinguishes it from traditional deep focus is that
there is not continuous depth of field from foreground to background; the space
between the two sharp objects is out of focus. Because split focus diopters only
cover half the lens, shots in which they are used are characterized by a blurred
line between the two planes in focus. Manipulated deep focus is not a new
phenomenon, as it had also been created in other ways during the golden age of
20th century. The diopter gave the opportunity for spectacular deep
focus-compositions that would have been impossible to achieve otherwise. In the
American New Wave, director Brian De Palma explored the possibilities of the
split-focus diopter extensively, as did other 70s films such as Robert Wise's
The Andromeda Strain and Star Trek: The Motion Picture.
Use in modern films Starting in the 80s, American cinema has
developed a trend that film scholar David Bordwell calls intensified
continuity. Bordwell claims that 1) The average length of each shot in a film
has become shorter over the years. 2) Scenes are built up by closer framing.
3) More extreme focal lengths are used. 4) The scenes include an increased
number of camera moves. This trend has led to deep focus
becoming less common in Hollywood movies. As mentioned in Bordwells'
second point, master shots where two or more characters hold a conversation have
gone out of fashion, lessening the need for deep focus. In a contemporary
Hollywood movie a dialogue scene may consist only of tight close-ups, with
the master shot abandoned. If more than one plane in the image contains
narrative information, filmmakers switch focus instead of keeping both focal
planes sharp. In addition, modern sets tend to have less lighting for more
comfortable working conditions, and use of deep focus tends to require more
light. The development of intensified
continuity may be due to directors' desire to capture the action or dialogue
from many different angles and views. Getting these shots is called coverage.
The U.S. film critic Dave Kehr explains it this way:
If there is a single word that sums up the difference between filmmaking at the
middle of the 20th century and the filmmaking of today, it is "coverage".
Derived from television, it refers to the increasingly common practice of
using multiple cameras for a scene. To stage a whole scene in one shot is no
longer common. Director Steven Soderbergh claims:
That kind of staging is a lost art, which is too bad. The reason they no
longer work that way is because it means making choices, real choices, and
sticking to them. That's not what people do now. They want all the options they
can get in the editing room. Notable uses
The following films and television programs contain notable examples of
deep-focus photography: See also
Depth of field Hyperfocal distance
Shallow focus References
Further reading Bordwell, David; Kristin Thompson. Film
Art: An Introduction. New York: McGraw-Hill.