רעיון שבור תאריך the focal point ברית חבובו חיננית
What Is Focal Length and How to Use It - 42West
File:Convex lens - Object between focal point and optical centre.png - Wikimedia Commons
The Importance of a Focal Point
How to Choose The Right Focal Point in Photography
Understanding Your Camera: Revisiting Focal Length : Martin Pot - Photography Blog
Principal focal point (two of them)
Focal Point - Convex Lenses
Thin lens - Wikipedia
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