represented by color temperature. These terms are used
in photography to describe and define the sources of
light being used.
light. Color temperature is based on what is called a
Planckian radiator, or simply a black body. As the
temperature of the metal of the black body is raised, it
goes from a dull black through red and orange to blue
and finally to white heat. The quality of the light emitted
is a function of the temperature of the metal. When the
object is red-hot, the color temperature is low since red
is at the low end of the scale; and when it is blue-white,
the color temperature is high. However, the temperature
at which a light source is burned does not control color
temperature; for example, a fluorescent tube burns at a
temperature then is raised or lowered relatively by the
Be careful not to get confused. Traditionally reddish
light is known as warm and bluish light as cold; in
actuality, the color temperatures is the other way around.
temperature. From a practical point of view, this term
refers to the degree of whiteness of the light. Color
temperature is measured on the Kelvin scale and is
stated as Kelvin temperature. On the temperature scale,
0 K is the same as -273°C. Therefore, degrees Kelvin
(K) are always 273 degrees higher than the same
temperature on the Celsius scale. Thus a red-hot piece
of iron with an approximate temperature of 2000°C has
a color temperature of 2273 K. As the Celsius
and produces a relatively higher color (Kelvin)
agreed that color can be defined by three qualities: hue,
brightness, and saturation.
For example, it could be said that the color of an object
the visible spectrum. These seven hues are as follows:
blue, green, red, cyan, magenta, yellow, and white. Hue,
however, is an inadequate description of a cola. To be
more specific, we should say that an object is dark blue
or light blue. Now we have described the brightness of
hue but different brightness. Thus, to describe a color or
brightness, we say that it is dull, bright, vivid, or
brightness. You can think of it as mixing black, gray, or
white paint with a colored paint, thus diluting the color.
In other words, saturation is a measure of color purity.
one or more of the following ways:
reflection is orderly, or specular. Specular light is
reflected at the same angle to the surface as the light
incident to the surface; that is, the path of the light
reflected from the surface forms an angle exactly equal
to the one formed by its path in reaching the surface.
Thus the angle of reflection is equal to the angle of
incidence, which is a characteristic of specular light
(fig. 1-6, view A). However, when the object surface is
not smooth and polished but irregular, light is reflected
is reflected in more than one direction.
light, and rough surfaces more diffused light. Since
diffused light is more common than specular light, it is
of greatest value in photography. Objects that are not
light sources are visible and therefore photographic.
Basic Photography Course