A dumb question/explanation, but wouldn't that be because the screen/viewing pane is flat, while your eye is a ball? Another way to visualize that calculation,

A dumb question/explanation, but wouldn't that be because the screen/viewing pane is flat, while your eye is a ball? Another way to visualize that calculation, is to see it as if it's adding a curved lens on top of the viewing pane. I have no idea what I'm talking about, though.