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.
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.
A convex lens is made from a transparent material that bulges outwards in the middle on both sides. It can focus light so that appears to meet at a single point, called the focal point. Light is refracted as it passes into, then out of, the lens.
Convex lenses are found in: