Nature is an amazing combination of hills, streams, jungles, various species of birds, and wildlife. Everything in nature cannot be observed in detail with naked eye. You need an instrument to make your vision clear and magnified if you are observing distant objects. These instruments which are called optics manipulate light and deliver it to the eye or digital or chemical film. These instrument use lenses or mirrors in the forms of monocular, binoculars, telescopes and microscopes.
Binoculars magnify and intensify light to both eyes and are used for sky and terrestrial viewing. Spotting scopes are used for bird watching and in shooting range to fix the target. Telescopes are mainly designed for astronomical purpose. All these instruments magnify and clarify the vision. Some of these optical instruments are designed with night vision capabilities. These instruments process invisible infrared images into visible images on the screen. They enable the user to see things clearly almost in total darkness. Choosing optics according to the purpose is very important.
An optical instrument is classified into two numbers one multiplied by another like 7*35 or 10*50 .These numbers refers to the magnifying
power of the instrument and the diameter of the lens in millimeter. All optical instruments are magnifying and light intensifying in nature. That is why choosing optics needs a lot of attention on the part of the user.