Samenvatting
The photopic sensitivity function needs a revision at the long wavelength side of the spectrum for two reasons. First the sensitivity values decrease exponentially as a function of wavelength. This is incorrect in view of present data. Secondly the photopic sensitivity function shows non-justified irregularities. A proposal is made to implement for wavelengths beyond 640 nm the present view that sensitivity decreases exponentially as a function of 1/wavelength by applying data of the CIE 1964-observer. For the covering abstract see ITRD E123380.