Manual of Photography, 9th Edition

13Spectral Sensitivity of Photographic Materials

The inherent sensitivity to light of the silver halides is confined to the limited range of wavelengths absorbed by them. This range includes the blue and violet regions of the visible spectrum, the ultraviolet region and shorter wavelengths extending to the limit of the known spectrum, including X-radiation and gamma-radiation. This applies, in general terms, to all types of emulsion – chloride, bromide, iodobromide, etc. – though the position of the long-wave cut-off of sensitivity varies with the type of emulsion, as shown in Figure 13.1. The amount of light absorbed in the inherent sensitive region, and hence the useful speed of an emulsion, depends on the volumes of the individual silver halide ...