Panchromatic Materials

black-and-white sensitized materials with a response to green, yellow, and red rays (wavelength from 500 to 700 nm). Panchromatic materials are to be distinguished from orthochromatic materials, which are sensitized only to green and yellow rays. In daylight the additional light sensitivity is 50 to 60 percent of the total light sensitivity of the photographic emulsion, and under incandescent lamp illumination it is 60–70 percent.

Two types of panchromatic materials are produced: (1) panchromatic materials proper, which have a relatively lower sensitivity to green rays, and (2) isopanchromatic materials, which have a uniform sensitivity to all visible rays. Negative photographic materials used in professional and amateur photography and cinematography are isopanchromatic with a somewhat lower sensitivity to red rays (wavelength from 660 to 700 nm); this corresponds to the color sensitivity of the average human eye. Panchromatic materials are used with orange or red filters in aerial photography, in color separation reproduction, in contrast separation of red parts of an object, and in other applications. Isopanchromatic materials are processed in the dark, but panchromatic materials proper, having a lowered sensitivity, may be processed in dark green light.