A minor correction to Jeremy's description of how to
white balance. Most cameras (video and digital still cameras) have a
manual white balance, as well as several presets and auto. White balancing essentially tells the camera what "white' should be, and then the cameras electronics adjust the red, blue and green sensitivity levels accordingly. Auto
white balance has the camera "guesses" based on some algorithims the cameras mfg came up with, (based on average light and subject conditions.) The most common presets: Indoors (a lightbulb symbol) , Sunlight (a sun symbol), Overcast outdoors (a symbol with clouds), and flourescent (a horizontal rectangle supposed to look a flourescent light tube). Some cameras may have other presets.
Finally there is the
manual white balance setting. to properly
manual white balance you should
zoom in and focus on a white card or paper lit by the same lights lighting your key subject (I.E. Center
Stage podium.) Then you hit the
manual white balance button and the camera adjusts accordingly. The paper or card should look white.
Common mistakes white balancing:
1: Not using the same kind of light as your key lights: If your
key light is a discharge lamp (like many arc follow spots) and you
white balance to an
incandescent ellipsoidal, your images will look very blue. Likewise if you balance to the arc, and your
key light is
incandescent, the video will be yellow.
2: Mixing lights of different color temps. I.E. using arcs and incandescents both to keylight the subject. the solution to this is to color correct one of the fixtures (usually the arcs with a full
CTO:
Lee 205)
3: Balancing to a paper that isn't white. If you use a yellow paper, the camera will subtract yellow from the images and everythhing will appear blue. Another related problem is reflected color. If you are using the proper light on a white paper, but the paper is next to a yellow wall, that wall may reflect yellow onto the paper, altering your
white balance. If you get a chance,
play with white balancing on different surfaces to see the results.
4: Balancing to a light with colored
gel. If you use a
ParCan with a red
gel, you probably want the subject to look red. If you balance to that light with the
gel still in, your camera will try to make red look white. Pull the
gel, balance, then re-gel.
5: Balancing without filters. If you use filters on the camera, balance with the same filters you will be using, otherwise the filters will tint the
image (unless that is a particular
effect you want. The exception is with some polarizing filters. You should balance, then put the polarizer on.
Ultimatly, the fixtures you describe, (pars, fresnels and ellipsoidals) are all
incandescent and have a
color temperature of 3200K. Using the "indoor" or "
incandescent"
white balance preset should work. The exception to this is if there are large windows letting lots of sunlight in. Sunlight color temp varies from 2000K to 10000K depending on time of day and cloud
cover. In that case you are best off manually white balancing each time you use the cameras.
Hope this helps
