Binoculars are vital for a host of military applications, bird watching hobbyists, hunting enthusiasts, and also budding astronomers. The basic setup for a majority of binoculars is virtually identical, but specialized use has led to single component---or multiple component---improvements and add-ons. Examples of such add-ons are various coatings, the addition of nitrogen in the binoculars' interiors, and also external paraphernalia that help to stabilize them.
Look through the eyepiece of your binoculars. This part of the apparatus is noticeably smaller than its opposite end, the objectives.
Feel for this adjustment tool while looking through the eyepiece. It is a ring that is situated directly behind the eyepiece lenses and permits for individual focusing of these lenses. Glasses or contact lens wearers--whose eyes have different optical strengths--appreciate diopter rings, since these allow for individualized focusing.
Find the focus wheel near the eyepiece, in between the lenses. It is a dial that allows you to slightly move the interior lenses, thereby bringing images into focus. This is crucial for those wearing glasses, since their eye conditions vary from the healthy eyes of others, necessitating an overall adjustment of the lenses for a sharper image.
Note that the prisms are located in the handle portion of the binoculars. These prisms are made of glass. Prisms receive the light from the objectives and reflect it to one another. The longer the handle portion, the more prisms are installed in a particular pair of binoculars. The more prisms there are, the more magnification you may enjoy.
Examine the diameter of the objective lenses. Located opposite the eyepiece, these are noticeably bigger. Their main role is to capture available light and feed it safely to the eyepiece. These lenses also provide the main gateway for providing sight of the intended target. Damaged objectives may render binoculars virtually useless, since scratches and nicks can alter the light availability.