A
good pair of binoculars is your most
important tool in identifying a variety of
birds. If you have never used binoculars
for this purpose you will be amazed at the
detail and color you will see. A whole new
world is about to open up.
There
are several characteristics shared by all
binoculars that are well suited for bird
watching. Your old pair of opera glasses
does not have any of them. (Well, they are
light weight.) These are some of the key
points to consider when selecting a new
pair of binoculars.
1.
Magnification
Most binoculars will have a series of
numbers printed on the body of the
binocular, usually just below the eye
piece. You will see a number like 7 X 35
or 8 x 42 or 10 x 50.
The
first number, the 7 , 8 or 10, is the
"power" of the binocular. Objects seen
through a 7x binocular will appear 7 times
closer than they really are. Objects seen
through a 10x binocular will appear 10
times closer than they really
are.
Most
bird watchers prefer a 7x or 8x binocular.
Lower powers do not provide enough
magnification and higher powers have a
narrow field of view and can be difficult
to hold steady.
2.
Exit pupil - Light gathering
capability
The second number is the diameter of the
objective lens, which is the lens on the
big end of the binocular. It is a measure
of the diameter of the lens in
millimeters. Thus a 7 x 35 binocular has
an objective lens with a 35 mm. diameter
and a magnification of 7 times.
The
diameter of the objective lens has an
effect on the "light gathering" or image
brightness of the binoculars. In general,
the larger the diameter, the brighter the
image. More specifically, the diameter of
the objective lens divided by the
magnification provides a good indication
of the potential light gathering
capability of the binocular. The higher
the number the better.
A
7 x 35 binocular is 35 divided by 7 or a
5.0 ratio, which is considered good. Avoid
binoculars that have a ratio much below 5,
such as a 7 x 30 or 7 x 25.
3.
Field of
view
Another number that is usually printed on
the body of the binocular is the field of
view. A large field of view makes it
easier to locate a particular bird. You
will usually see the field of view
measured in terms of viewing angle ( 6
degrees, for example) or 400 feet at 1000
yards. Avoid binoculars that have a field
of view under 6 degrees or less that 300
feet.
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4.
Close focal
distance
Another key factor in selecting the right
binocular is the shortest distance down to
which the binoculars can focus. Some of
the less expensive binoculars available in
the department and discount stores will
only focus down to about 30 feet or more.
There will be many occasions when you will
want to be able to focus down much lower
than this. Some binoculars designed for
bird watchers can focus down as close as
5-6 feet.
The
close focus distance is not usually marked
on the binoculars. You'll have to test
them yourself or ask the person from whom
you are purchasing the
binoculars.
5.
Eye glasses
relief
The eye relief determines how far your eye
can be from the eyepiece while still
allowing a full field of view through the
binocular. This is important to eyeglass
wearers. Look for a High Eye Relief design
if you plan to wear glasses while using
your binoculars. 15 mm or
greater.
6.
Design
There are two standard designs utilized in
binoculars. The porro prism design has an
offset barrel. The roof prism design has a
straight barrel. The roof prism design has
historically been lighter in weight,
slightly smaller and more expensive.
Either design, however, is
acceptable.
7.
Size and
Weight
The size and weight of the binoculars can
make a difference if you become an avid
birder and spend hours in the field. The
choice is a personal one, however, and you
may need to try several pair to find the
ones that you like best.
8.
Lens
coatings
Many binoculars tout special lens coatings
and special types of glass. The special
coatings are designed to provide increased
brightness and clarity to the image. Some
binoculars can cost well over $1000.00 and
feature exotic glass and
coatings.
Binocular
Selection Check
List
|
Feature
|
Recommendation
|
Magnification
|
7x35, 7x42, 8x40 or
8x42
|
Field of View
|
Minimum 6 degrees or 300
feet at 1000 yards
|
Close Focal
Distance
|
20 feet or less
|
Eye Glass
Adapter
|
Rubber
cups or similar device - 15 mm
minimum eye
relief
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A
wide selection of quality binoculars is
available from the
Birdzilla store.
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