Binoculars come in various sizes and are the most widely used optical tool other than eye glasses. Used for hunting, camping and many other outdoor activities as well as indoors at sporting events and concerts, binoculars magnify an object allowing for a better view from a distance. Some models can be large and bulky in size or compact and your activities or viewing needs will help you determine what size you require. Most models used for hunting offer a camouflaged finish for concealment in the field. The following will help you understand how binoculars are sized and how they work so you can be assured to get the best pair for your viewing pleasures.

Binoculars Specifications

• Magnification x Lens Diameter

  All binoculars are referenced by the power of magnification x lens diameter for example, 10 x 50. The first number (10) represents how many times larger an object will appear from its normal size when viewed. The second number (50) represents the diameter in mm of the forward or object lens.

  When determining magnification you must consider the typical viewing distance you require. The higher the magnification number, the more difficult it will be to view close or moving objects. The size of the object lens determines the amount of light it will gather. The larger the number, the brighter the viewing area especially in low light conditions. The larger lens also means a larger and heavier pair of binoculars.

• Brightness

  The brightness as mentioned is greatly affected by the size of the object lens. The amount of brightness is determined by the size of the exit pupil which is the result in mm of the lens diameter divided by the magnification. An exit pupil of 3 mm to 5 mm is good for normal viewing conditions and anything larger is better suited for viewing in low light.

• Prisms

  The purpose of a prism is to correct the inverted and reversed images you would see in their absence. The prisms are located inside the binoculars and they transmit light from the objective lens to the eyepiece. Binoculars are available with one of two prism options: porro prism and roof prism. Porro prism offsets the eyepieces from the objective lens to allow more brightness to be let in and makes the binoculars larger in size. Roof prism aligns the lenses in a straight configuration, which makes the design smaller. The smaller models are more preferable but the image is not as bright as with a porro prism.

• Field of View

  The Field of View specification is the side to side view in feet at 1000 yards. Binoculars with higher magnifications tend to have a smaller field of view. A wider field of view is more favorable for stalking and hunting wildlife from a distance or in wide open areas.

• Focus

  There are generally three focus features on each pair of binoculars. Some models offer fixed focus, which is convenient but loses the ability to change the focus as needed. A center knob lets you focus both barrels at the same time. The right diopter ring, located on the right eyepiece, allows you to customize your focus for each eye. Binoculars are also ranked on near-focus distance or focal point, which is how far away you must be from an object before it can be properly focused. The general range is 10-40 feet.

Other features you may consider are anti fogging lenses or rubber or ‘armor coated’ bodies to protect damage if the binoculars are dropped. Any added features usually means added price and binoculars can range from very low in price (less than $30.00) to very high dollar binoculars. A good pair of binoculars will last a lifetime with proper care and when it comes to optics, quality is usually worth the investment.