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Tips On Buying Binoculars For Birding

The first part is from Birding.com Binocular Buying Guide with my underscoring and one parenthetical note. My own suggestions are noted.

Magnification

Generally, the range in magnification for hand-held binoculars is from 6 to 10 in power. In a binocular designation (7 X 35, for example) the first number indicates the magnification, or how much larger, or closer, the object will appear than seen with normal vision. When considering magnification, more is not necessarily better. As magnification increases, brightness and clarity may diminish, depth of field can become shallower and the field of view is usually more restricted. More noticeable and disturbing at higher powers are fine hand tremors and the effects of atmospheric conditions, such as the distortion caused by heat waves.

If your observation is done primarily at close range, such as in woodland areas or in your backyard, then a good 6, 7 or 8 power binocular might be the best choice. This range of magnification generally gives you a larger picture (wider field of view) which is especially important for viewing objects relatively close at hand. Also, binoculars of this magnification usually deliver better performance under conditions of low available light, due either to the time of day, weather conditions, or shadows caused by dense vegetation or other structures. This same type of binocular also works well for fast-moving action like sporting events, since the wide field of view allows the action to remain in the viewing area.

For long distance viewing or where greater detail is required, a higher magnification of 8, 9 or 10 should be considered. For example, the demands of observing in wide open terrain with little cover are best met with a binocular of 9 or 10 power. This generally holds true for situations where there is a need for critical field mark identification, as in observing raptors and shorebirds or when the object or animal is difficult to approach. Magnification, as a binocular parameter, should be considered as it relates to other factors such as aperture size, exit pupil, hand-held stability, atmospheric conditions, available light, optical design and the weight of the binocular.

Aperture

The second number of a binocular designation refers to the diameter, in millimeters, of the front, or objective lens. The diameters usually range from 20 to 50 millimeters and this number will almost always be directly related to the size of the binocular. The objective lens size, or aperture, determines the amount of light that will enter the optical system. The common assumption that the size of the objective lens will determine the field of view is seldom true as field of view is controlled largely by the optical design of the binocular.

A larger objective lens will gather more light and theoretically provide greater detail and clarity of the image. This is especially true under low light conditions (like around here). Since the amount of light that will enter the objective lens will vary by the square of the change in the radius, a small difference in objective lens size will have a greater impact on the light gathering ability than one might first suspect. Once the objective gathers the light into the binocular, other factors determine how much light is transmitted through the optical system and all of these factors, including the aperture, combine to determine the brightness and clarity of the image you actually see. These other factors include magnification, exit pupil size, eye pupil size (controlled largely by the amount of available light), the presence and type of anti-reflection coatings used, and the size and quality of the optical glass and prisms used in the construction of the binocular.

Woody's recommendations

A good versatile pair of binoculars is somewhere in the 8X40 range. Ten- power magnification works well if you have steady hands, don’t mind the extra weight and are mainly going to bird in open areas, like wetlands, over water or in plains. Moderately priced ($300-800) but high performance binoculars include:

If you are willing to swallow hard and pay $1,000-$2,000 for even better binoculars, consider:

Four more important considerations in selecting binoculars:

Spend as much as you can afford. Binoculars are a lifetime investment, and will bring years of enjoyment of birds, wildlife and other natural wonders.

Good Birding! Woody