Influence of Field Size on the Spectral Sensitivity of the Eye in the Photopic and Mesopic Range

The relative spectral sensitivity was measured at luminance levels ranging from scotopic to near photopic vision. This was done for various photometric field sizes of 3 to 64° in diameter. The spectral absorption of the macular pigment seems to account for the difference in the blue part of the spectrum occurring between small and larger fields. The influence of the field size in mesopic levels depends on lithe spectral region. In order to define the mesopic standard observer, the Commission In‐temationale de I'Eclairage (CIE) has suggested a set of curves which were partly based Jon experiments obtained under different conditions. It could be shown that these curves, nearly coincide with those obtained with the 64° field. The V 10° (λ) curve derived from color equation measurements could be confirmed as a luminance efficiency curve obtained by direct brightness match measurements.