Abstract

The specific character of the S-cones with respect to the Stiles-Crawford effect can be deduced from measurements by Stiles and Crawford (1939), and Alpern and Katahari (1983), who showed that the luminous efficiency of the S-system at an eccentricity of entry of the light of 3 mm, is ~30–40% lower than the efficiency of the M- and L-systems. Bouman and Walraven (1960) assumed a reduced luminous efficiency of the same order of magnitude of the S-system to explain the chromatic Stiles-Crawford effect in the 400-500-nm wavelength region. I suggest that this difference between the S-system on the one hand and the M- and L-systems on the other, be attributed to the scarcity of the S-cones. In the case of the S-cones the oblique incident light leaks to M- and L-cones but not to other S-cones because the separation between the cones is too large. It is suggested that all cones exhibit a Stiles-Crawford effect equal to that of the S-cones, but that the effect for the L- and M-cone-systems is reduced because of the leakage of light to neighboring cones.

© 1991 Optical Society of America