Binocular: is a pair of tubes fitted with an objective and an eyepiece in which magnified images of distant and near objects are seen. Binoculars for distant objects are called opera glass. In prism binoculars, prisms are used for reducing the length of the scope tube. It consists of a pair of right-angled totally reflecting prisms. One prism reverses the image. formed by the objective, upside-down and the other from left to right.