Binocular – No one model or brand of binocular will provide the perfect viewing solution in every habitat, climate, terrain, weather, or light condition. So the most important consideration in choosing the right binocular is determining its primary use and then consider how its optical characteristics will directly affect its flexibility for use in other applications. Before you can properly determine what type of binocular that you will need, you should familiarize yourself with the information provided in the Binocular Terms, Anti-Reflective Coatings and Binocular Prism Systems postings. Exit pupil, eye relief, field of view, focus systems, magnification, objective lens, and prism systems are all issues to understand when selecting the appropriate binocular.
A binocular is really two mini telescopes aligned to give you stereoscopic vision, which is more comfortable for your eyes and has the advantage of allowing for better depth perception. When you see things with both eyes simultaneously, your brain blends these two separate images into one three-dimensional image with a greater field of view. This blended image provides you with up to 40% more detail than you can see with either eye alone through a spotting scope.
A binocular is specified by two numbers separated by an “x”. For example, with an 7×50 designation, the first number represents the power of magnification, where the object being viewed appears to be seven times closer than you would see it with the unaided eye. The second number in the formula (7×50) is the diameter of the objective front lens in millimeters (mm). The larger the objective lens, the more light that enters the binocular which results in a brighter image with higher contrast and greater clarity. To further improve the viewing, an anti reflective coating is deposited on lens surfaces to reduce light reflection off the glass lens and allow more light to pass through to your eyes. A binocular can range from a mini to compact size that can fit in your palm or your pocket up to the giant binoculars with objectives lens sizes of 60mm or more made for astronomy and extreme long-range viewing.
Rubber armor provides multiple benefits for a binocular: protects it from the bumps and scratches that come with day-to-day use; provides a comfortable and more secure gripping surface; easy surface to clean; and suppresses noise if the binocular bumps aluminum or other non-rubber surfaces.
A waterproof/fog proof models utilizes an O-ring that is sealed and nitrogen-purged so they are totally waterproof. As a result, interior optical surfaces will not fog due to rapid changes in temperature or humidity. This model can withstand complete immersion in water and still allow the internal components to stay safe and dry inside the binocular.