I’ve always wondered about this, so I’m glad I was finally able to get an answer. Long story short:
The human eye is equivalent to a 576 megapixel camera and has a nighttime ISO of 800 (~1 during the daytime).
It’s actually pretty cool how this guy figured it out. I read through most of the material and while I didn’t go through and check all his calculations, it seems pretty solid to me. Here’s the good stuff:
Based on the above data for the resolution of the human eye, let’s try a “small” example first. Consider a view in front of you that is 90 degrees by 90 degrees, like looking through an open window at a scene. The number of pixels would be
90 degrees * 60 arc-minutes/degree * 1/0.3 * 90 * 60 * 1/0.3 = 324,000,000 pixels (324 megapixels).
At any one moment, you actually do not perceive that many pixels, but your eye moves around the scene to see all the detail you want. But the human eye really sees a larger field of view, close to 180 degrees. Let’s be conservative and use 120 degrees for the field of view. Then we would see
120 * 120 * 60 * 60 / (0.3 * 0.3) = 576 megapixels.
The full angle of human vision would require even more megapixels. This kind of image detail requires A large format camera to record.