Color Correction

A major use is to compensate the effects of lighting not balanced for the film stock's rated color temperature (usually 3200 K for professional tungsten lights and 5500 K for daylight): e.g., the 80A blue filter used with daylight film corrects the orange/reddish cast of household tungsten lighting, while the 85B used with tungsten film will correct the bluish cast of daylight. Color correction filters are identified by numbers which sometimes vary from manufacturer to manufacturer. The use of these filters has been greatly reduced by the widespread adoption of digital photography, since color balance problems are now often addressed with software after the image is captured.

Although the 80A filter is mainly used to correct for the excessive
redness of tungsten lighting, it can also be used to
oversaturate scenes that already have blue.
The photo on the left was shot with
a polarizer, while the
one on the right was
shot with a polarizer
and an 80A filter.