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Binoculars (Part 2)

In addition to magnification, consider these factors:

  • Size of Objective Lens - Binoculars are identified as "8X40" or "7X42" or "10X50," for example. The number before the X is the power, or magnification, and the second number is the diameter of the lens at the front of the binoculars in millimeters. The larger the front lens, the more light your binoculars will collect and the more detailed the image should be. Lens size around 40 is normally optimal. The largest you'll usually find is 50, generally in a 10X50 instrument. Compact binoculars with lenses smaller than 30 often give you too small an image to be worth considering.
  • Size, Weight and Comfort in Your Hands - Old-fashioned porro-prism binoculars (the lenses are set farther apart than the eyepieces) tend to be bulkier and heavier than roof-prism models (their lenses are aligned with the eyepieces). However, quality porros are are roughly one third the price of quality roof models.
  • Close Focus Capability - If you are interested in up-close views of small objects, like butterflies, look for binoculars that can give you a sharp look at things only a few feet away.
  • Weatherproofing - Higher-end models will be sealed from outside air that can fog interior surfaces in humid or rainy weather.
  • Eye Cups - To shade users' eyes against the sun, the eyepieces have either soft rubber or hard plastic cups. If you wear glasses, you must either roll down the soft rubber or push in the hard plastic to get your eyes closer to the eyepieces for an adequate view.
  • Other qualities to look for include
    • Ease of Focusing
    • Sharpness of Image
    • Trueness of Colors
    • Brightness of Image in Twilight
    • Glare-Reducing and Scratch-Resistant Lens Coatings
    • Durability (Shock Resistance)

Personal preference also plays a major role

in choosing binoculars. After researching the features of binoculars, you are well advised to get some hands-on experience with various models, preferable out in the field, before deciding on which to buy.

Return to Part I to learn about binocular magnification.

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