Editing Color temperature (section)

===Photographic film===
{{unreferenced section|date=June 2012}}
Photographic emulsion film does not respond to lighting color identically to the human retina or visual perception. An object that appears to the observer to be white may turn out to be very blue or orange in a photograph. The [[color balance]] may need to be corrected during printing to achieve a neutral color print.  The extent of this correction is limited since color film normally has three layers sensitive to different colors and when used under the "wrong" light source, every layer may not respond proportionally, giving odd color casts in the shadows, although the mid-tones may have been correctly white-balanced under the enlarger.  Light sources with discontinuous spectra, such as fluorescent tubes, cannot be fully corrected in printing either, since one of the layers may barely have recorded an image at all.

Photographic film is made for specific light sources (most commonly daylight film and [[tungsten film]]), and, used properly, will create a neutral color print. Matching the [[sensitometry|sensitivity of the film]] to the color temperature of the light source is one way to balance color. If tungsten film is used indoors with incandescent lamps, the yellowish-orange light of the [[tungsten]] incandescent lamps will appear as white (3200&nbsp;K) in the photograph.  Color negative film is almost always daylight-balanced, since it is assumed that color can be adjusted in printing (with limitations, see above).  Color transparency film, being the final artefact in the process, has to be matched to the light source or filters must be used to correct color.

[[filter (photography)|Filters]] on a camera lens, or [[color gel]]s over the light source(s) may be used to correct color balance. When shooting with a bluish light (high color temperature) source such as on an overcast day, in the shade, in window light, or if using tungsten film with white or blue light, a yellowish-orange filter will correct this. For shooting with daylight film (calibrated to 5600&nbsp;K) under warmer (low color temperature) light sources such as sunsets, candlelight or [[tungsten lighting]], a bluish (e.g. #80A) filter may be used. More-subtle filters are needed to correct for the difference between, say 3200&nbsp;K and 3400&nbsp;K tungsten lamps or to correct for the slightly blue cast of some flash tubes, which may be 6000&nbsp;K.<ref name=":0">{{Cite book|last=Präkel|first=David|url=https://books.google.com/books?id=VHBUDwAAQBAJ&q=photography+lighting+kelvin&pg=PP1|title=Basics Photography 02: Lighting|date=2013-02-28|publisher=Bloomsbury Publishing|isbn=978-2-940447-55-8|language=en}}</ref>

If there is more than one light source with varied color temperatures, one way to balance the color is to use daylight film and place color-correcting gel filters over each light source.

Photographers sometimes use color temperature meters. These are usually designed to read only two regions along the visible spectrum (red and blue); more expensive ones read three regions (red, green, and blue). However, they are ineffective with sources such as fluorescent or discharge lamps, whose light varies in color and may be harder to correct for. Because this light is often greenish, a magenta filter may correct it. More sophisticated [[colorimetry]] tools can be used if such meters are lacking.<ref name=":0" />