Color Temperature of a light source describes the spectrum of light which is radiated from a theoretical “blackbody” (an ideal physical body that absorbs all radiation and incident light – neither reflecting it nor allowing it to pass through) with a given surface temperature.
Or. Most simply it is a method of describing the color characteristics of light through a numerical value that corresponds to the color emitted by a light source, measured in degrees of Kelvin (K) on a scale from 1,000 to 10,000.
More accurately. The color temperature of a light source is the temperature of an ideal backbody that radiates light of comparable hue to that of the light source.
The focal length of an optical system is a measure of how strongly the system converges or diverges light.
Without getting into an in-depth physics discussion, the focal length of a lens is an optical property of the lens.
The exact definition is:Focal length measures the distance, in millimeters, between the “nodal point” of the lens and the camera’s sensor.
