Photography 101

[footfootfoot]

Originally Posted by Clodfobble

But my retina doesn't move like the left-side line in your picture.

That's right. Your eyes have a fixed focal length and thus a fixed angle of view.

Originally Posted by Clodfobble

What about when the left line sits still, but the two lines on the right move farther apart from each other (up and down, respectively)?

That doesn't affect your angle of view, that changes your depth of field, or degree of sharpness.

degree as in extent, not fraction of a circle.