Magnification of Binoculars

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.

Thanks to our friends at Eagle Optics for providing this information!

See also:
Spotting Scopes—Tips for choosing the right spotting scope
Birding Tripods—Tips for choosing the right tripod for you binoculars and scopes

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