How to choose Binoculars

A binocular consists of two optical systems that are joined by a hinge and (typically) share a common focusing mechanism. The ability to create an image for both eyes simultaneously provides a realistic perception of depth. Binoculars are available in a great variety of sizes, magnifying powers and features to suit any purpose or preference.

Binoculars always come in handy - whether you are an avid hunter or an occasional day hiker. They are essential gear for camping and hiking, a day in the field or a holiday trip to the grand canyon. Choosing the best binocular for your needs is not always easy. Consider when, where and how often you plan to use them in order to select a binocular with a combination of features that are right for you.

MAGNIFICATION (POWER)

Binoculars are often referred to by two numbers separated with an x. For example; 8x32. The first number is the power or magnification of the binocular. With an 8x32 binocular, the object being viewed appears to be eight times closer than you would see it with the unaided eye.

OBJECTIVE LENS SIZE

The second number in the formula (8x32) is the diameter of the objective or front lens. The larger the objective lens, the more light that enters the binocular, and the brighter the image.

COATED OPTICS

Lens surface coatings reduce light loss and glare due to reflection for a brighter, higher-contrast image with less eyestrain.

• Coated - A single layer on at least one lens surface.
• Fully Coated - A single layer on all air-to-glass surfaces.
• Multi-Coated - Multiple layers on at least one lens surface.
• Fully Multi-Coated- Multiple layers on all air-to-glass surfaces.

FEILD OF VIEW(F.O.V.)

The side-to-side measurement of the circular viewing field or subject area. It is defined by the width in feet or meters of the area visible at 1000 yards or meters. A wide-angle binocular features a wide field-of-view and is better for following action. Generally, the higher the magnification, the narrower the field-of-view.

RESOLUTION

Resolution, or definition, is the ability of a binocular to distinguish fine detail and retain clarity.

EXIT PUPIL

Refers to the size of the circle of light visible at the eyepiece of a binocular. The larger the exit pupil, the brighter the image. To determine the size, divide the objective lens diameter by the power (an 8x32 model has an exit pupil of 4mm).

EYE RELIEF

The distance a binocular can be held away from the eye and still present the full field-of-view. Extended or long eye relief reduces eyestrain and is ideal for eyeglass wearers.

PRISM SYSTEMS

The prism system of a binocular reduces the size needed to provide focal length and turns what would be an upside-down image right-side-up. There are two types of prism systems, roof and porro.

Roof Prism System - In roof prism binoculars the prisms overlap closely, allowing the objective lenses to line up directly with the eyepiece. The result is a slim, stream-lined shape in which the lenses and prisms are in a straight line.

Porro Prism System - In porro prism binoculars the objective or front lens is offset from the eyepiece. Porro prism binoculars provide greater depth perception and generally offer a wider field of view.

Prism Glass

Most optical prisms are made from borosilicate (BK-7) glass or barium crown (BAK-4) glass. BAK-4 is higher quality glass yielding brighter images and high edge sharpness.

Rainguard is the Bushnell Bino hydro-phobic (water-repellent) coating on which condensation from rain, fog or snow forms in much smaller droplets than on standard coatings. Smaller droplets scatter less light which results in increased light transmission and a clearer image. Makes the binocular useful even when looking directly into the driving rain.

Phase Coating

Phase Coating forces light beams back into perfect phase, which eliminates the ?soft? image effect found in roof prism binoculars and results in superior image resolution, contrast and clarity. Without this coating, due to their more intricate prism design any roof prism binocular will have light waves slightly out of sync, and therefore a dimmer and fuzzier image.

?soft? image effect found in roof prism binoculars and results in superior image resolution, contrast and clarity. Without this coating, due to their more intricate prism design any roof prism binocular will have light waves slightly out of sync, and therefore a dimmer and fuzzier image. (see illustration)