The Single Lens Camera
A single small lens or pinhole projects the outside world, upside down, onto a screen inside a darkened box — the same basic idea every camera, including your eye, is built on. This is a real image — light actually converges on the screen.
Point the camera at different objects. Ask your friend to wave their hand at the camera. Can you see the inverted image move as the real scene moves?
Additional Information
The image lands upside down because light travels in straight lines, crossing over itself as it passes through the tiny opening. This “camera obscura” idea is centuries old — artists once used darkened rooms with a single hole to trace accurate outdoor scenes.
Your own eye works almost the same way: a lens at the front projects an upside-down image onto your retina, and your brain flips it right-side up.
In your textbook