(idea) by stylee Fri Dec 15 2000 at 15:25:45
Sources of artifical light can produce various washes in your color photographs; it is important to be aware of the effects produced by different kinds of light so you can either use them to your advantage or avoid them altogether.

Most indoor household bulbs give off tungsten light and lead to yellow-colored photographs. This is not necessarily a bad thing; many photographers (Nan Goldin, for one) have used this effect wisely and purposefully - it can add emotional overtones to your photographs ranging from warm and welcoming to dank and ancient. However, if you don't want the yellow overtones, this can be compensated for in the darkroom (or in photoshop) by adding extra blue to the image.
(btw: in the darkroom, 'adding blue' means turning up the yellow in your color pack...I won't get into all that here.)
It is also possible to use tungsten-balanced film to alleviate the problem altogether. However, if that film is used outside under beautiful, natural light, strange things happen.

Florescent lights result in an overall green muddy look on film. Our eyes are used to how things look under flourescent lights; we may not notice how sickly and awful people look under them until they are caught on film. You can compensate for that by adding magenta to the image, again either in the color pack on your enlarger or in a photoshop-esque program.

A little manipulation with color settings can make a world of difference for problems due to artificial light sources. But beware that whenever you resort to dramatically changing the color balance in your program settings or enlarger, you can lose alot of detail, crispness and contrast in the image.

One way to get around dealing with these problems is to use the flash, your camera's very own and very purposeful artificial light source. The flash takes care of the yellow you'll get from tungsten lights; it attempts to create a white light similar to what you might find outside. However the flash causes its own problems if you are bothered by the fact that the direct bright central light on your subject has *flash!* written all over it. It also takes away alot of the beautiful patterns and shadows you might enjoy with overhead or side lighting.

Of course, professional studio photographers needent worry about any of this hoo-hah because they can employ a vast array of standing lights and colored cells to produce any effect they desire. But for photographers who prefer the spontaneity of 'real life' shooting to the calculatedness of the studio, standing lights aren't necessarily practical or available. In this case, if you must shoot in the dark and want to avoid that blatant, head-on flashy look, a remote flash is a god send. This enables you to utilize the good aspects of having a flash around, but not be limited to the direct, head on direction of an on-camera flash.
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(idea) by m_turner Thu Mar 14 2002 at 2:26:02
Artifical lighting can be broken down into two types:
  • Continuous spectrum (incandescent)
  • Non-continuous spectrum

Most incandescent lights today are tungsten fillment type. Using daylight film indoors leads to a yellow to reddish tint in the negative. There are several approaches to correcting this tint:

All of these correct in different ways and it is up to the decision of the photographer to choose which one is most appropriate for the situation. Tungsten-balanced film is often more expensive and only comes in slides rather than print type. A flash is the most popular however some people have issues with the washed out appearance that often accompanies a flash and difficulties with getting the exposure correct (see flash guide number). Using a filter is a very good choice, however it often causes a significant reduction in light reaching the film (up to two stops) leading to longer exposures (reasonable if things don't move but hard to get people to hold still for a second or two). See color balance and color temperature for more information.

As the natural light becomes more important, some light manufactures have created lights that closely mimic the spectrum of daylight. These are often used for light therapy, pets that are sensitive to the light, and people trying to get accurate color representation (painters, photographers, etc...). These lights produce a 5500 K color temperature and have a very high Color Rendering Index. These lights are often labeled as "full spectrum" or "neodymium". (Links for more information at the bottom)

While the incandescent bulbs have a full range of the spectrum, light from exciting a particular element (rather than warming it up) has gaps in it. Some of these are rather sizeable such as light from an LED or low pressure sodium vapor lamp. Others are good enough for our eyes but the true color (or lack of) comes out on film.

Picture a color wheel with red, green and blue 120 degrees apart from each other - white is at the center. 

red
    ,-'""`-.
  ,'\       `.
 /   \        \
(     \        )
|      >-------| Green
(     /        )
 \   /        /
  `./       ,'
    `-.,.,-'
blue
On this circle, picture a curve from red to blue with a bulge at green: 
red
    ,-'""`-.
  ,'\       `.
 /   \        \
(     \        )
|      )       | Green
(     /        )
 \   /        /
  `./       ,'
    `-.,.,-'
blue
This is the "ideal" curve. The amber and blue filters from color temperature adjust the bulge up and down. If the image is too warm (bulge near red), adding a blue filter will pull this bulge down. There are times however, that this bulge doesn't go far enough or goes too far. This is often the case of a deficiency in the light or a tinting of the light.

The classic fluorescent lighting is considered poor in magenta (red + blue) or strong in green. In this case, the bulge points too strongly at green and needs to be adjusted back. To do this, often a magenta filter is used.

Each "style" of fluorescent lighting has a different spectrum that is stronger or weaker in different colors than others. Often film manufacturers will publish a table to help photographers correct for the color deficiencies of various lights and the film characteristics (remember: not all film is the same). For fluorescent if you don't know with daylight film, a bit of magenta (30M) is recommended. With high energy discharge lights need a bit of yellow in addition to the magenta (yellow + magenta = red) and thus a 30R or 40R filter is often suggested.

Realize, that some lights (such as the low pressure sodium vapor) are futile to try to balance. Furthermore, shooting under mixed lighting is futile. If exact tones of color is important run a color test.

Nikon's table as a general recommendation for daylight and tungsten balanced film:: 

    | Day     | White   | Warm    | Warm      | Cool    | Cool White
    | Light   |         | White   | White Dlx | White   | Delux
----+---------+---------+---------+-----------+---------+-----------
Day | 40M+40Y | 20C+30M | 40C+40M | 60C+30M   | 30M     | 20C+10M
Tun | 85B+40M | 60M+50Y | 50M+40Y | 10M+10Y   | 60M+60Y | 20M+40Y
... | +40Y    |

    | GE      | GE         | Clear    | Delux White
    | Lucalox | Multivapor | Mercury  | Mercury
----+---------+------------+----------+-------------
Day | 70B+50C | 30M+10Y    | 80R      | 40M+20Y
Tun | 50M+20C | 60R+20Y    | 90R+40Y  | 70R+10Y

The following table is from Photographer's Filter Handbook: 

\ Light| Day     | White   | Warm    | Warm      | Cool    | Cool White
Film \ | Light   |         | White   | White Dlx | White   | Delux
-------|---------+---------+---------+-----------+---------+------------
Agfa   | 50R     | 40M     | 40M+10Y | -         | 20C+20M | -
Fuji   | -       | -       | -       | -         | -       | -
 Velvia| 40R+10M | 40M+10B | 80C+25M | -         | 40M+05R | -
 Provia| -       | -       | -       | -         | -       | -
  100F | 30R+10M | 25M+20B | 80B+15M | -         | 35M     | -
  ...  |         |         | +10R    |           |         | -
  400  | 40R+05M | 40M+10B | 80C+20M | -         | 30M+10R | -
 Astia | 35R     | 15M+20B | 80B     | -         | 30M     | -
 64T   | 85B+40R | 85B+81D | 30R+05M | -         | 85B+25M | -
 ...   |         | 40B+10M |         |           | +10R    |
 Print | 30R     | 10C+20M | 30B     | -         | 20M     | -
Kodak  | -       | -       | -       | -         | -       | -
(print)| -       | -       | -       | -         | -       | -
 Porta | -       | -       | -       | -         | -       | -
  160  | 20R+05M | 40B+05C | 40B+40C | 40B+50C   | 30B     | 40C+10M
  400  | 20R+05M | 40B+05C | 40B+40C | 40B+50C   | 30B     | 40C+10M
  800  | 40R     | 30C+40M | 50B+05C | 40B+40C   | 30M     | 20B+20C
 Supra | -       | -       | -       | -         | -       | -
  100  | 40R     | 30B+10M | 50B     | 40B+40C   | 05B+20M | 20B+20C
  400  | 30R+05M | 30C+40M | 60B     | 55B+40C   | 05C+30M | 20B+20C
  800  | 40R     | 30C+40M | 50B+05C | 40B+40C   | 30M     | 20B+20M
(slide)| -       | -       | -       | -         | -       | -
 Kodachrome
  25   | 50R     | 40M     | 20C+40M | 30B+30C   | 40M+10Y | 20C+10M
  64   | 50R+10M | 05C+40M | 20B+20M | 40B+05C   | 40M+10Y | 05B+10M
  200  | 30R     | 10B+05M | 40B+05C | 10B+50C   | 20M     | 05B+20C
 Ektachrome
  100  | 50R     | 40M     | 20C+40M | 30B+30C   | 40M+10Y | 20C+10M
  200  | 50R     | 40M     | 20C+40M | 30B+30C   | 40M+10Y | 20C+10M
  64T  | 85B+40M | 05R+10M | 50M+40Y | 10R       | 60R     | 20M+40Y
  ...  | +30Y    |
For unknown fluorescent lamps with Kodak:
  • Porta 160, 400: 40B+40C
  • Kodachrome 25; Ektachrome EPP, 100, 200: 30M
  • Kodachrome 64: 05C+30M
  • Kodachrome 200: 10B+05C
  • Ektachrome 64T: 50R
Kodak also publishes a table for high density discharge lamps: 
       | High Pressure | Mercury | Metal Halide | Metal Halide
       | Sodium 2700K  | Vapor   | 4300K        | 3200K
-------+---------------+---------+--------------+-------------
(print)| -             | -       | -            | -
 Porta | -             | -       | -            | -
  160  | 50B+70C       | 30B+05C | 05C+10M      | 80C+10M
  400  | 50B+70C       | 30B+05C | 05C+10M      | 80C+10M
  800  | 60B+50C       | 30M     | 05R+20M      | 20B+30C
 Supra | -             | -       | -            | -
  100  | 55B+50C       | 30M     | 50R+20M      | 50C+20M
  400  | 55B+50C       | 20B+30M | 30M+05Y      | 30B+05C
  800  | 60B+50C       | 30M     | 05R+20M      | 20B+30C
-------+---------------+---------+--------------+-------------
       | GE Lucalox    | GE Merc | Delux White  | Clear
       |               | Vapor   | Mercury      | Mercury
-------+---------------+---------+--------------+-------------
(slide)| -             | -       | -            | -
 Kodachrome            | -       | -            | -
  25   | 80B+20C       | 20R+20M | 30R+30M      | 70R
  64   | 70B+30C       | 30R+10M | 30R+30M      | 120R+20M
  200  | 50B+70C       | 20R+10M | 10R+30M      | 110R+10M
 Ektachrome
  100  | 80B+20C       | 20R+20M | 30R+30M      | 70R
  200  | 80B+20C       | 20R+20M | 30R+30M      | 70R
  64T  | 50M+20C       | 60R+20Y | 70R+10Y      | 90R+40Y

http://www.lumenlight.com/
http://www.naturallighting.com/articles/choosing_the_right_light.htm
http://www.topbulb.com/find/full_spectrum.asp?REF=36

Photographer's Filter Handbook
The Nikon Field Guide

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