^Image formation rules
^Image formation rules
1. A ray passing through optical center of any lens convex or concave at any angle to principal axis goes undeviated.
2. An oblique passing through focus of any lens convex or concave at any angle to principal axis becomes parallel to principal axis after refraction.
3. A ray parallel to principal axis of any lens convex or concave axis meets or appears to be meeting focus after refraction.
