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using color gels to
alter the white balance of the video image
experience level: beginner -
everyone can learn this
There are many options
available to videographers and cinematographers
to control color
balance – gels on lights, practicals and windows, filters on lenses.
One additional technique
available to D.P.'s shooting with video is the use of standard
color-correction gels to alter the results of white-balancing.
By placing an appropriate light gel over the camera
lens during a white-balance,
one may purposely shift the balance in-camera to achieve creative
effects.
Warm
Cards
There has been some
excitement over the Warm Cards recently introduced to market.
warm cards
Warm Cards are used by
pointing a video camera at a tinted card (rather than the usual white surface)
and hitting the white balance switch. The result is a color cast
opposite that of the card. For instance, balancing with a WARM 1
card results in a shift in color equivalent to
1/4 CTO.
If you take a glance at the Warm Cards,
you'll note they look a lot like a paper version of
CTB color correction gels.
Better
than Warm Cards
The downside of Warm Cards
for the micro-budget shooter is they cost $65-95! That's
quite a bit for the student filmmaker. But, you can achieve the
same results as Warm Cards with another, readily available, tool -
and spend nothing!
Any handy lighting gel may
be used in the same fashion as Warm Cards. If you want to warm
your image slightly, grab a 1/4 CTB
gel and, while pointing the camera at a white surface illuminated by the
key light, place the gel over the lens and hit the white balance switch.
Even better,
Lee Filters
makes a 2"x3" gel swatch book that any D.P. or cameraman
can keep in their ditty bag, ready to whip out in front of the
camera lens. Most gear rental shops keep a box of these handy at
the counter. Look for the "Cinematographer's Edition".
lee filter swatch books
Below are samples
of a Kodak color patch and gray scale chart as well, as frames from
narrative projects,
after a JVC GY-DV500 camcorder was white-balanced through various
color-correction gels.
.
white-balanced reference - JVC GY-DV500
all settings at defaults except -3dB
Mole 407 1K - 320 F.C. - 12.9 EV
3200K white-balance with tungsten light
5600K white-balance with daylight
warming by white-balancing through CTB
none, 1/8, 1/4, 1/2, 3/8, full
1/4 CTB
1/2 CTB
cooling by white-balancing through CTO
none, 1/8, 1/4, 1/2, 3/8, full
1/8 CTO
1/4 CTO
1/2 CTO
cooling by white-balancing through L.C.T. Yellow (Lee 212)
none, Lee 212
fluorescent simulation by white-balancing through minus green
none, 1/8, 1/4, 1/2, full
1/8 -GREEN
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