Focal Length: An Easy Guide to Using and Understanding Camera Lenses
Lesson 4 Define the terms principal axis, focal point, focal length and linear magnification as applied to a converging (convex) lens. Define the power. - ppt download
optics - What is the actual significance of the focal point of a lens? - Physics Stack Exchange
Understanding Focal Length and Field of View | Edmund Optics
Focal Length Explained: A Beginner's Guide – Camera Harmony