A recurrent problem in geometrical optics: a not perceived image discontinuity at the magnifying glass

Abstract

Could we be looking at an object across a magnifying glass without perceiving the sudden image inversion - from virtual and erect to real and inverted - when the object moves away from the lens to a place a little farther than the focal distance? In this article we show that this effectively happens, as well with some eyeglasses lenses, like common reading glasses.

magnifying glass; human eye; geometrical optics