Hearing about rod versus cone vision and only really knowing that cones are for colour and are concentrated in the center of our FOV (field of view); I finally did a little reading.
I thought that cones had the high angular resolution, and the rods had low angular resolution. I can't give any measured numbers for the resolution but I did find out a few physiological details.
There are approximately 8,000,000 cones in the average persons eye. They are almost exclusively in the center of our vision. The cone density peaks about about 150,000 per square mm. I thought wow.
Then I read that there are about 120,000,000 rods. The peak rod density is about the same as the cone peak density. The rod peak density is located in the area around the region of cones. The density for about half (maybe 2/3 I didn't note it too well) of our FOV has a rod density greater than 75,000 rods per sq. mm. And at the edge of our FOV the density is still at 20,000 rods per sq. mm.
The rods are radiometrically more sensitive than the cones, but are spectrally indiscriminate.
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Just throwing a couple of more pennies on the piles. Blame it on KWLee, he said rods. 
