Many people in the world enjoy their choice of sports using these gadgets with designs which can go from compact and light, to the bigger, full-sized models. Police surveillance teams and people involved in government intelligence also find a set of binoculars an indispensable tool in their jobs.

Bird watchers also make up a large number of binocular users in the world. Their personal satisfaction of watching birds in these animals? natural environment is only made memorable with the use of high-power binoculars.

These people require more from their binoculars. Their gadgets must have the needed viewing power to meet their needs, lightness for easy transporting, and most importantly, durability to last years of continuous use. These viewing gadgets must be easy to hold, and protected from moisture and dirt. The resolution of a binocular must be able to reveal details and true colors accurately. They must also be able to quickly focus and work well in weak lighting conditions. Lastly, these gadgets must be able to show the real picture for bird watchers wearing eyeglasses and contact lenses.

Binoculars are easy to use and more advantageous than telescopes and monoculars. They allow viewers to use both of their eyes simultaneously, and viewers are offered a superior experience, allowing them to follow fast movements easily. These tools further allow easier viewing of fast moving objects such as race horses than a telescope of monocular.

Binoculars work by passing the image through two adjacent lenses and prisms. The prisms then revert the image, by the internal reflection of available incoming light. Images are then displayed right side up rather than inverted as what astronomical telescopes do. The magnified image then becomes available to the viewer's both eyes.

The magnifying power of a binocular is described by two numbers separated by ?x?, e.g., 3x10. While the first number determines the magnifying power, the second number displays the objective lens? (the lens which is further from the eye) diameter in millimeters. Models varies from small, compact 3x10 models which are usually used in theaters, to the average 7x50 and 10x50 for outdoor purposes. The larger models such as 20x80 and 20x140 are sometimes called ?galaxy models?.

Large binoculars are more like telescopes, and their high magnifying capacity needs fixed mounting. This is necessary to avoid small movements being magnified which makes viewing difficult. Because of this drawback, standard hand-held binoculars are now limited to 9x or 10x.

Today, binocular models use either Porro prisms or roof prisms. Porro prism binoculars were the standard models up to the 1960s. Later on, the Zeiss and Leitz companies introduced to the market new models using roof prism.

These new models were light, compact and easier to hold, and they looked simpler than the models using Porro prisms. But because roof prisms use a more complicated light path and needed greater optical precision in their production, these roof prism binoculars cost more to manufacture. The Porro prisms, on the other hand, had a simpler design, and are more efficient as their images displayed better contrast.