Manual
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OVERVIEW
Although motion capture is ultimately just a steady
stream of stills, how one thinks about exposure,
equipment and workow all require reorientation.
Storage requirements are higher, exposure is linked to
the frame rate, and image editing needs to consider
the entirety of a clip, for example. In exchange, one
gains a whole new creative dimension: time. Where
one could previously show a moment, now one can
depict an extended story.
The terminology is also dierent, in part because
of the more recent roots in lm. For example, color
editing is referred to as “grading,” quick-turnaround
imagery is referred to as “dailies,” manually focusing
is called “pulling focus,” and a single image is referred
to as a “frame” or a “still,” amongst other dierences.
This article focuses more on introducing high-level
concepts than language though, and links to related
tutorials are also provided if a closer look is needed.
SHUTTER ANGLE
The concept of a shutter angle is perhaps the most
fundamental yet unfamiliar for stills photographers.
In a nutshell, it describes shutter speed relative to
the frame rate, and is important because it controls
the extent to which motion blur in successive frames
blends together. At one extreme, a shutter angle of
360° means the shutter speed is as slow as possible,
and is equal to the frame rate. Then, as the shutter
speed is increased, the shutter angle becomes
progressively smaller.
OVERLAID MOTION BLUR
VS. 45° SHUTTER ANGLE
OVERLAID MOTION
BLUR VS. 180° SHUTTER
ANGLE
The key is that unlike with many types of photography,
some motion blur is often desirable with video, since
this helps smooth the dierence between otherwise
discrete frames.
VISIT THE "LEARN" SECTION ON RED.COM FOR THE
TUTORIAL ON SHUTTER ANGLES & CREATIVE CONTROL
FOR EXAMPLE VIDEOS AND ADDITIONAL DIAGRAMS.
© 2008 LEVERAGE HOLDINGS, INC. ALL RIGHTS RESERVED.
In general, a good balance between crisp stills and
smooth motion is achieved with a shutter angle near
180 degrees, which equates to a shutter speed near
1/50 of a second at 24 fps. Most cinematography
is therefore captured near this shutter speed.
Although this simplies camera settings, it has several
consequences for lighting and exposure…
LIGHTING & EXPOSURE
With stills, one typically adjusts the camera settings
to t the lighting, whereas with video, one typically
adjusts the lighting to t the desired camera settings.
A big reason for this is because with video, exposure
is ordinarily controlled using only ISO and lens
aperture. Imagine the necessary lighting and types
of photography that were possible at 1/50 second,
and that’s likely close to what you’ll have to work with
when shooting standard video.
Any exposure shortfall is then oset using higher
intensity, continuous lighting. For many, this is
unfamiliar territory — strobes and ash are no longer
the universal lighting tools they were with photography.
Since creating a bright pulse is much easier than
sustaining this continuously, lighting requirements
often increase substantially. However, once the
necessary equipment is in place, most photographers
actually nd video lighting to be easier, since subjects
are visualized under the same illumination as they’ll be
captured.
Exposure strategy also has to adapt. Whereas still
capture usually needs perfect lighting at a single
moment, motion capture has to consider how lighting
will vary over the duration of subject and camera
movement. Using the stills photographer’s strategy
of “expose to the right” therefore runs a high risk
of overexposure. With video, instead leaving spare
latitude above the highlights will help safeguard
against clipping.
VISIT THE "LEARN" SECTION ON RED.COM FOR THE
TUTORIAL ON EXPOSURE STRATEGY WITH RED CAMERAS
AND IN-CAMERA EXPOSURE TOOLS FOR IN-DEPTH
DISCUSSIONS.
LIGHTING FOR MOTION
(CONTINUOUS)
TYPICAL LIGHTING FOR
STILLS (STROBES OFF)
CINEMATIC LENSES
Sometimes photographers are confused when they
encounter the term “cinematic lenses,” but this quickly
subsides once realizing these have all the same
functionality as standard SLR lenses. The primary
dierence is performance: they are often larger and
sturdier, have stier and more smoothly adjustable
focus rings over a wider range of motion, and are
typically sharper wide open. Their aperture also isn’t
restricted to discrete values, and is instead controlled
using a continuous lens ring (similar to focus or zoom
with an SLR lens). In addition, most cinema lenses are
strictly manual focus since cinematographers typically
don’t use autofocus during a recording.
The other big exception is that cinematic lenses are
specied using a T-number instead of an f/number.
Although both terms describe the lens aperture,
each has a dierent emphasis. An f/number, as many
photographers will be familiar, is a ratio between the
lens focal length and the aperture diameter. A 100
mm lens at f/4 has an aperture diameter of 25 mm, for
example. This is extremely powerful because any lens
at f/4 will have equivalent depth of eld, but falls short
when describing exposure, since not all lenses at f/4
record the same amount of light.
The T-number solves the exposure problem, and is
eectively just the f/number with a correction factor
to account for light transmittance. An f/4 setting that
has 50% transmission eciency (a 1-stop reduction)
will therefore be specied as T5.6, for example. When
changing lenses, one therefore only needs the same
T-number, and all lighting can be kept identical. The
ip-side is that all T5.6 lenses won’t necessarily have
equivalent depth of eld, but they’ll usually be close
enough to preserve the creative intent.
STANDARD SLR
ZOOM LENS
EQUIVALENT CINEMA
LENS