Scale diagrams for convex lenses (including magnification)

In cameras and the human eye, the required image distance < the object distance so the image is diminished and inverted. In projectors, the required image distance > the object distance so the image is magnified and inverted. A ray incident on a convex lens parallel to the principal axis is refracted to pass through principal focus. A ray incident on the centre of a convex lens is not refracted. A ray incident on a convex lens from the principal focus is refracted so it becomes parallel to the principal axis.