There are multiple lenses inside the scope, not just a differentiation you see, you can see the sight as a long tube, he is not just a point, but also the parallax problem caused by the quality of the sight, a good sight is {0 parallax, that is, no matter where the eye looks in, it is equivalent to you aiming from the center Kedudukan.
Sama ada optik or reflektif, the red dot is the same.