What is shown is that the closer to the eye an object is,
the bigger the image, the more strongly curved the eye's lens is, and the
shorter the focal length becomes.
Additionally, this applet shows ray tracing diagrams for converging lenses.
Notes:
The eye is not anatomically correct.
The top ray does not actually enter the eye but can still
be drawn to find the position and size of the image.
When the object gets very close to the eye, the applet
will show an image bigger than the retina, indicating the eye would see
only part of the object.
