8
Maximizing Depth
When viewing 3D films, audiences accustomed to scanning the real 3D world tend to
explore the entire contents of the frame, believing they are free to focus and converge
their eyes wherever they choose. As a result, viewers may experience eyestrain when they
try, without success, to resolve objects on the screen which are out of focus—objects that
are beyond the lenses’ depth-of-field. For this reason 3D filmmakers generally opt to use
lenses with a wide depth-of-field, lenses that, in the case of 1” camera imagers, have a
focal length of 50 mm or under. Not only do longer lenses shrink the depth-of-field, but
they foreshorten perspective. And because of this they can produce potentially disturbing
cardboarding
effects—the illusion that objects in the scene are merely cutouts, lacking
modeling or depth. This artifact can be counteracted, to a degree, by choosing a wider
interocular, thereby restoring some of the depth to the scene. But choosing this option
risks introducing unwanted miniaturization effects, as noted above. Unless, for some
reason, a filmmaker specifically wishes to use artifacts such as soft focus, cardboarding,
and miniaturization as storytelling devices, it is generally considered advisable to avoid
long focal-length lenses in 3D productions. This restriction on the choice of lenses
unfortunately deters most 3D filmmakers from using one of the most effective of 2D
filmmaking tools—the application of selective focus as a way to direct the audience’s
attention to the subjects the filmmaker considers to be of primary importance on the
screen. Because of this, 3D
filmmakers must pay renewed attention to the power of light,
color, and composition to draw attention to the subjects in the scene that they want the
audience to see. For example, a street that winds away into the distance can help to set
the actors apart from the background, or the use of smoke, dim lighting, or cooler hues
can help to direct the audience’s attention to foreground subjects that are more clearly
defined, more brightly lighted, or shaded in warmer tones.
In addition, to take advantage of the unique capabilities of 3D, scenes may be composed
in a way that emphasizes the depth of the set. In this regard, a set that includes multiple
layers of depth may be preferable to one that includes only a few layers of depth. As an
example, while a 2D cinematographer might stage a conversation between two actors as
they stand against a wall, a 3D filmmaker, to take full advantage of the medium, might
prefer to stage the same scene with the actors conversing as they stroll down a street,
passing other pedestrians and moving through multiple layers of depth. As with any
medium, however, the ability to add depth to a scene does not obligate a filmmaker to use
the full complement of depth-enhancing tools. The 3D filmmaker is free to capture
flattened images, if such images most effectively express the intent of a scene.
Managing Motion
Because 3D images require more time to scan and fuse (or
read
) than 2D images, viewers
may be frustrated by overly-rapid camera and/or subject motion. To avoid this reading
lag, 3D filmmakers often choose to slow the pace of the camera movement and to stage
on-screen action either at a slower pace or at a diagonal relative to the camera. In the
same way,
because 3D is intrinsically more subjective, more interactive, and
explorative
than 2D, filmmakers working in 3D generally opt to keep their cameras in motion,
allowing the cameras to travel slowly and smoothly through successive layers of depth—
i.e. relying less upon static shots and more upon carefully-planned camera choreography
to engage the audience in the story.
