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Binoculars

Whether you want binoculars for bird watching, general nature study, sports, or sightseeing, there are a number of factors to consider.

  • Magnification - How close the binoculars make a distant object seem is called "magnification." For example, magnification of 8X (often called "8 power") makes an object 80 feet away appear as if were only 10 feet away. Is more magnification better? Not necessarily. These is a downside to greater magnification:
    • Hand Tremor - no one can hold binoculars perfectly still. As magnification increases, you are more likely to notice that the image shakes. Windy conditions or on a boat (as in whale watching) only increases the problem.
    • Field of View - people with normal eyesight have a field of vision that radiates roughly 160 to 170 degrees in both the left-right and up-down dimensions. Most 7X binoculars have a field of under 9 degrees, which shrinks to about 5 degrees with 10X binoculars. With a smaller field of view it becomes harder to find an object, especially a moving one like a flying bird.
    • Depth of Field - people with normal eyesight (or good eyeglasses) can look off in the distance and see everything from a few feet away to the horizon with roughly equal clarity. With binoculars, once you focus on a distant object, other objects more than a few feet in front of or behind your subject will be out of focus. At greater magnification, the in-focus range usually becomes narrower.
    Therefore for most purposes, 7X or 8X binoculars are safer bets than 10X. Note, however, that field of view and depth of

    field can vary between instruments with the same magnification based on the quality of manufacture.

Learn about other factors, such as size of the objective lens, comfort, close focus, weatherproofing, eye cups, and other qualities.

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