Fig. 8. Acceptance angle vs pupil absorbance calculated for three visual pigment conditions, pure rhodopsin (R), one (R+S) and two (R+2S) sensitizing pigment molecules per rhodopsin, for photoreceptors with distal rhabdomere diameters 1.4-2.0 µm. For each of the seven pupil states the acceptance angle as well as the total absorption of a uniformly radiating sky were calculated. The pupil absorbance was obtained by taking minus the decadic logarithm of the absorption relative to that for the dark-adapted state (h=; the case of Fig. 6).