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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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