Fig. 3.

Range–color–focus relationship for a 10-mm-diameter cephalopod lens. Colored lines show the accommodation vs. range relationship at the 500-nm opsin peak sensitivity and the FWHM of the spectral resolution that we estimate for the chromatic focusing hypothesis. For objects more distant than R_d, there is an unambiguous relationship between wavelength and the accommodation setting that makes the sharpest image. For objects closer than R_d, an independent determination of range is needed to break the degeneracy between range and color.