SOME ASPECTS OF ISO SENSITOMETRIC DAYLIGHT

The current ISO sensitometric daylight illuminant and its colorimetry are described and the range of permitted tolerance in its realization is explored in terms of simple, practically achieved, filter adjustmen ts monitored by spectroradiometry. An extensive calibration of a sensi tometer is reported and a simplified method suitable for routine opera tion is described as an adaptation of a previously published method fo r the determination of the photographic colour temperature of an illum inant. The use of CIE colorimetry in the calibration of a sensitometer is shown to be misleading and radiometry emerges as the appropriate m ethod of calibration to match ISO requirements.