For all practical purposes, the general classes of emulsions are considered insensitive to the shorter wavelengths of ultraviolet (UV) radiation. Light-sensitive emulsions are sensitive to all wavelengths of ultraviolet radiation. Others respond to only a narrow band of wavelengths. Some of these emulsions respond to a wide range of wavelengths of light. The four classes are as follows: colorblind (monochromatic), orthochromatic, panchromatic, and infrared. There are four general classes of black-and-white film emulsions. The color sensitivity determines how the film is classed. The color sensitivity of a black-and-white film is an important characteristic, since it controls the way colored objects record as tones of gray in the negative
Increasing the color sensitivity of an emulsion to other than ultraviolet, violet, and blue is called dye, color, or optical sensitization. The addition of sensitizing dyes to silver halides can increase the sensitivity of emulsions and extend their sensitivity to green and red light and infrared radiation. Color-blind emulsion is the term given to emulsions sensitive only to these radiations. Color sensitivity or color response refer to ultraviolet and infrared radiation as well as visible light.Īll silver halides are sensitive to ultraviolet radiation, violet, and blue light. In this chapter, the terms color sensitivity and color response are used interchangeably. Also, emulsions have color sensitivity, which means they are sensitive to one or more colors of the visible spectrum. Spectral sensitivity of an emulsion simply means that the emulsion is sensitive to some energy of the electromagnetic spectrum. When speaking of film or emulsion sensitivity, you are also referring to its sensitivity to ultraviolet and infrared radiation. You already know, from our earlier study of light in chapter 1, that the visible spectrum is made up of violet, blue, green, and red light. The response of an emulsion to specific colors of light or radiant energy is termed coIor or spectral sensitivity.
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