The field trials of the 10°-field supplementary standard observer proposal performed by W. S. Stiles and G. Wyszecki on the National Research Council three-primary Donaldson colorimeter have been repeated on the National Bureau of Standards Donaldson colorimeter. Only the least selective 11 of the 18 NRC filters were used in the NBS repetition, which employed 11 observers each making two sets of matches. The NBS Donaldson colorimeter with a 10°-field of view was calibrated both in terms of the 1931 CIE standard observer system and in terms of the 1959 supplementary proposal. As expected, visual matches with a 10° field compared quite unsatisfactorily with predictions made by the 1931 standard observer. The results are in general agreement with the Stiles–Wyszecki field-trial data. The agreement with the predictions by the 1959 proposal is improved when the results of the two field trials are combined, because the resulting arrays of individual-observer data encompass the predicted chromaticities of all of the filters but the red one. It is concluded that, although the proposal is not completely satisfactory, it does yield a significant improvement over the agreements achieved between predictions by the 1931 observer and observations.
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