You’re both right, to some degree. While you are correct that the eyes focus at a certain depth, much like a camera, the difference is that we can chose to focus at any depth (assuming good eyesight). This is not true of a photograph if it has no depth. (It’s also true that, if the photograph has both fore and background in focus, edges may be harder to pick out and depth harder to discern, even though we would have no trouble with our own eyes. That’s the basis of much trick photography, after all!)
All photos are unnatural. To quote the artist (and, dare I say, photographer) David Hockney: “I mean, photography is all right if you don’t mind looking at the world from the point of view of a paralyzed cyclops—for a split second.”
At risk of this becoming too long-winded, allow me to point out another “normal” variable of photography that is wholly unnatural (beyond the issue of focus and the fact that one moment is extended to infinity): Shutter speeds faster than 1/150s or slower than 0.5s. Our own eyes will never see the individual blade of a helicopter so clearly as a simple iPhone camera will when shot against a bright sky. Nor will naked eye see a waterfall as a blurry, peaceful average the way a long exposure portrays it.
Dynamic range too. Modern digital sensors are just now approaching dynamic range similar to that of the "instantaneous" dynamic range of human eyes, but as you mentioned we don't really see images instantaneous as a camera does and what we "see" (when you include brain processing) is really essentially a stack of everything we've seen up to as much as the previous 15 seconds; and when you take that into account even the best cameras are still way off on DR.
All photos are unnatural. To quote the artist (and, dare I say, photographer) David Hockney: “I mean, photography is all right if you don’t mind looking at the world from the point of view of a paralyzed cyclops—for a split second.”
At risk of this becoming too long-winded, allow me to point out another “normal” variable of photography that is wholly unnatural (beyond the issue of focus and the fact that one moment is extended to infinity): Shutter speeds faster than 1/150s or slower than 0.5s. Our own eyes will never see the individual blade of a helicopter so clearly as a simple iPhone camera will when shot against a bright sky. Nor will naked eye see a waterfall as a blurry, peaceful average the way a long exposure portrays it.