Artifical lighting can be broken down into two types:
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