We test the hypothesis that the diameters of foveal and near-foveal rods and cones for one well-studied human photoreceptor mosaic and one well-studied monkey photoreceptor mosaic (Macaca fascicularis) a scaled relative to focal length. We conclude that this hypothesis is not supported. Rather than being scali proportionally, the sizes of the rods and cones, respectively, are nearly equivalent for both the human ar monkey resulting in an effectively finer retinal grain for the larger human eye. Furthermore, the human density exceeds the monkey rod density beyond about 1 deg of retinal eccentricity. These results suggest variation across primate species is reflected in retinal sampling strategies.
