The Logical Formation of the Pinhole Eye
The formation of the pinhole eye is quite simple, and requires little space to explain. Imagine a cauldron-like eye. Just as the eye formed in the first place, it shall now evolve further. The eye will experiment with many different shapes over time. Evolution will prevail with the pinhole eye due to a smaller hole where light comes in, which causes the more directional light to reach the photoreceptors, and less interference affecting the resolution of the image (Nilsson, 303). This can bring about a relatively high resolution, as far as non-lens-containing eyes are concerned. In fact, the resolution is comparable to the vision of mammals, reptiles, and amphibians. There is a disadvantage to the pinhole eye, however. With a limited area for light to enter the eye, images will be darker than in a lens-containing eye. For nautiluses, the trade-off seems to be worth it, for they have survived this long.
Vision Through the Eye of a Nautilus
Looking through the eye of a Nautilus, as mentioned above, would be well focused. It will also be darkened due to the limited amount of light reaching the photoreceptors. It is not noted how many different types of photoreceptors are in the nautilus eye, so the color sensory has been limited.