● Binoculars are simply two telescopes side by side, one for each eye. When light rays from a distant object pass through a convex lens, they cross over. That's why distant things sometimes look upside down if we look at them through a magnifying glass.

● Two objective lenses are situated at each end of the binoculars. The purpose of the objective lens is to collect light from the object that the user is looking at and bringing the collected light into focus in the eyepiece lens, which creates a visible and magnified image.

● The image generated is backwards and inverted. Corrective elements known as prisms are used to fix this problem and they are situated between the objective lens and the eyepiece lens.

● The prisms used in binoculars are basically blocks of glass that acts like mirrors. The prisms use internal reflections to bring the beam of light from the objective lens closer together and to correct the orientation of the image created by the objective lens.

● Two types of prisms are used in binoculars: roof prisms and porro prisms.