What To Know When Buying Binoculars

Author: Chuck Fitzgerald

We are asked nearly every day: "What are your best binoculars?"
And every day we answer: "How do you plan on using them?" We are
not trying to be evasive with our answer, but the truth of the
matter is – the best binoculars for one purpose may be the worse
binoculars for another. We want you to Get It Right The First
Time.

Understanding your application is paramount in determining the
best fit – for you. Although there are many other specifications
and qualities which determine the usefulness of binoculars, we
will discuss in this article the primary characteristics for
determining the best fit for your application. But before we
show you the list, we should go over some basic terminology.
What do the numbers on binoculars mean? All sporting optics
(binoculars, spotting scopes, night vision goggles, etc.) use
the same nomenclature to describe important features. As an
example, a pair of binoculars may have 10x42mm listed as a
technical specification. But what does this mean? The "10"
refers to the magnification power of the binoculars – that is –
objects viewed will appear to be 10 times closer than when they
are viewed by the naked eye. The second number in our example is
"42mm." This refers to the diameter, in millimeters, of the
objective lenses on the binoculars. The objective lenses are
located on the end of the binoculars furthest away from your eye
when viewing. As with the aperture of a camera lens, the size of
objective lens determines the amount of light that can enter
your binoculars. If your binoculars are going to be used during
low light (hunting and astronomy are good examples) you had
better have large objective lenses. Another important number
describing binoculars is called field-of-view. A field-of-view
of 390' indicates that the width of the sight picture is 390
feet at a distance of 1000 yards. Field-of-view is determined by
magnification and the focal lengths of the objective and
eyepiece lenses. More magnification always means less
field-of-view. This specification is sometimes expressed in
degrees. A field-of-view of 6.5 degrees equates to 341' (6.5
times 52.5 equals 341). How well your binoculars will serve you
in low light conditions is described as Twilight Performance.
Although many things, such as overall design and quality of
glass impact this specification, magnification and objective
lens diameter are the chief components. A quick way to determine
the Twilight Performance of binoculars is to multiply the
magnification power (first number) times the objective lens
diameter (second number). The higher the result, the better the
Twilight Performance. As an example, 10x42mm binoculars will
have better Twilight Performance than 8x50mm binoculars (420
versus 400).

Now that we understand some basic terminology, here is “What to
Know When Buying Binoculars."

* While compact binoculars weigh as little as a pound, by using
them you will undoubtedly sacrifice performance. If performance
is your main consideration, full sized binoculars are preferred.
Anything weighing over about 1.5 pounds will get heavy fairly
fast. Use a binocular support system to evenly distribute the
weight across your shoulders instead of using a strap around
your neck. * The amount of light available while using your
binoculars will determine –more than any other consideration –
which binoculars are best for you. Low light uses such as
hunting, birding and astronomy require larger objective lenses.
* The distance you will be from the object you view will
determine the magnification power required in a pair of
binoculars. If your application is bird watching, theater or
sporting events, a low powered binocular will suffice in most
cases. But if you're into astronomy, you'll need a high powered
pair. * The minimum focal point in binocular terminology refers
to how near an object can be to you and be still be viewed in
focus. This tends to be important for birding but not so
important for most other uses. * Binoculars with a magnification
power greater than 10x (and without a stability feature) will be
difficult to hold steady. This becomes important when viewing
the night sky or distant mountains. A tripod may be a good thing
to have if you’re using binoculars with high magnification. *
Using your binoculars outdoors will usually subject them to
moisture. Waterproof binoculars are preferred for all marine,
hunting, birding and other nature related activities. * The
greater the magnification, the narrower the field-of-view. If
field-of-view is important to you, don't purchase the most
powerful binoculars you can find. This becomes very important
when viewing objects that move quickly such as antelope, race
horses, shooting stars or race cars. * As with almost everything
else in life, with binoculars you get what you pay for. There
are binoculars that cost under $10 and others which cost in
excess of $2,500. My experience says you will need to spend at
least $250 for a pair of binoculars worth having. * There is no
such thing as “one-size-fits-all” when it comes to sporting
optics. If you have multiple uses for binoculars, you will most
likely end up with multiple pairs of them – and that’s O.K.

Your understanding of these few simple tips will not only help
you in acquiring the correct binoculars for your application,
but they will also help you with successful viewing – no matter
what you’re looking at. Use this information and you’ll Get It
Right The First Time. Get Outdoors!

About the author:
Chuck Fitzgerald is Owner and President of Phoenix, Arizona
based BackCountry Toys, an online store providing backcountry
specialty gear and educational information to outdoor
enthusiasts. Visit www.BackCountryToys.com to receive the free
newsletter "FreshAir” or call (800) 316-9055.