Binoculars

Binoculars are handy devices that are used to view distant objects that cannot be clearly seen through the naked eye. These devices are composed of two mini-telescopes that can be adjusted to magnify objects. The user grips the binoculars by hand and holds the eyepieces of the telescopes against the his eyes. A rotating dial changes the distance between the various lenses in the telescopes so that a clear image can be seen.

The focus of both the telescopes in consumer binoculars can be adjusted simultaneously with a single dial placed in the centre of the device. In some professional binoculars, the on the other hand, there are separate adjustments for each telescope so that the focus of each can be fine-tuned individually. These adjustments perform two main functions; controlling the magnification of the image and changing the focus to prevent blurriness.

The optical mechanism used for magnification distinguishes binoculars into two main types; porro prism and roof prism. The former technique, named after the inventor Ignazio Porro, incorporates a double prism construction aligned in a zigzag manner. The latter type of binoculars are smaller but not as cheap and use objective lenses that are somewhat lined up along with the eyepieces. Binoculars are often used by tourists and birdwatchers. Just about anyone may find use for these devices. Some army binoculars have night vision facilities.