CHAPTER 2 INSIDE DIGITAL VIDEO CAMERAS^21
When a video calls for
the camera to move—say,
to follow someone who is
walking—the most com-
mon method to eliminate
distracting camera
movement is to use a
stabilizer, which is
essentially a long,
weighted stick.Although a video camera may have an auto-
focus mechanism, its lenses are also likely to
have a focus ringthe camera operator
can turn by hand for critical or creative
adjustments. Similarly, a hand-controlled
zoom gives the operator more control over
the speed at which a zoom takes place.3
Although consumer video cameras provide a range of
the latest high-tech recording media, from memory
chips to DVD to hard drive, with some exceptions
the professional video camera still uses digital
magnetic tapefor the images and sounds it
captures. The reason is the sheer quantity of
storage the cameras require. It’s an economic
decision influenced by the need to get the
most out of legacy equipment that would other-
wise depreciate too soon. Back at the studio,
though, tape is now usually transferred to computer
hard drives where an editor can usenon-linear editing
software. Older analog methods required editors to wind
through however much tape it took to get to the shots that would
actually be used. Non-linear processes let the editor go directly to
those scenes without having to plow through intervening footage.
Most professional cameras have a profusion of controls and jacks
for auxiliary equipment. Most common among these are con-
nections for handheld microphones or boom mikes. The
latter is a highly directional micr phone on the end of a
lightweight pole that the boom operator can twist to
point in different directions over the heads of people
speaking while keeping the microphone outside the
camera’s frame. Such microphones are necessary
because the mikes built into cameras often cannot
pick up wanted sounds without also receiving distract-
ing unwanted sounds.6
The beam splitter uses threedichroic prismsto
separate light into the three wavelengths—colors—and to
aim each at a different sensor. The surfaces of a dichroic
prism are coated with chemicals in a layer whose thickness
is one-fourth that of the wavelength of the light the coating is
designed to affect. The coatings, such as zinc sulfide and
titanium dioxide, interact differently with different wave-
lengths. One coating reflects light with a wavelength below
500nm (nanometers, or 1 billionth of a meter) to break out the
blue light. A second coat reflects light above 600nm, which sepa-
rates red light. Green, the remaining light, passes through both coats
without deviating from its path.5
The light focused through the
lens winds up hitting three
image sensorsrather than
the one found in the usual
family camcorder. First,
though, it goes through a
beam splitter that separates
the color into red, green, and
blue constituents—the same
three colors used in film and
digital still photography.4