Light can be focused so that it appears to meet at a single point. Focusing is important for getting clear images in our eye or in photographs. Images that are not focused appear blurred.

The pinhole camera

A pinhole camera consists of a box or tube with a translucent screen at one end and a tiny hole (the pinhole) made in the other end. Light enters the box through the pinhole and is focused by the pinhole onto the translucent screen. The image is upside down and smaller than the object.

Light enters a box through the pinhole and is focused onto the screen, with the image upside-down and smaller than the object.A ray diagram to show focusing in a pinhole camera