Binoculars are instruments similar to telescopes and are for terrestrial use (several observations). This instrument allows us to have a three-dimensional view of the observed objects, as it is built by two telescopes. Binoculars give us a straight picture; unlike telescopes, which provide us with a virtual, inverted image.
These instruments have several uses, from leisure, military purposes, to observing nature or watching a show. Binoculars are composed of an objective lens (which forms an inverted image), a set of prisms (which transforms the image into a straight image) and an eye lens (which magnifies the image observed). The figure below illustrates the layout of a binocular.
Figure: 1- objective; 2 – Porro prisms; 3 – lenses; 4 – eye
Binoculars are usually characterized by two numbers. One that indicates the magnification and one that indicates the objective diameter. Magnification is how many times the image of an object is magnified in relation to the object seen with the naked eye. The objective diameter is an important characteristic, as the larger the objective, the more light will enter the equipment.
By Domitiano Marques
Graduated in Physics
Brazil School Team