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A wide field makes it easier
to pick up and identify fast
flying birds. It makes it possible
to scan a sky, an ocean, or an
open marsh quickly. It’s also
easier to locate birds at close
quarters in a maze of
branches.
Birding binoculars should
also offer good depth of field –
a sharp, adjustment-free
image from near to far. A
generous depth of field assists
when trying to locate a close-
at-hand bird in a maze of
branches. A generous depth of
field mitigates the need to
make focus adjustments every
time a bird moves a little
closer or a little farther away.
Both field of view and depth
of field are closely related to
magnification. In general,
binoculars with lower
magnifications offer greater
depth of field, and a wider field
of view than binoculars with
higher magnification.
Eye Relief
Very closely related to field of
view, eye relief refers to the
distance between the ocular
lens and the human eye. This
distance is measured in
millimeters.
Eye relief is a very
important consideration for
birders who use eyeglasses in
the field and who do not
remove their eyeglasses when
fitting binoculars to their
eyes.
Because the eyes of eyeglass
wearers are already set 10-15
mm behind a glass barrier, they
demand a very “high" eye point
– a binocular that offers a
minimum of 15 mm of eye relief.
With rubber eyecups rolled down
or otherwise retracted,
eyeglass wearers can enjoy the
same wide field enjoyed by non-
eyeglass wearers.
NOTE: Just because a pair of
binoculars comes with rubber
eyecups does not mean they
offer good or even adequate eye
relief for eyeglass wearers. The
test is in the length of the
actual eye relief.
Weather Resistance/
Water Proof
Birding is an activity
conducted outside, and from
the moment a birder takes his
or her binoculars outside, the
outside is trying to get inside
those binoculars.
In general “Internal Focusing"
binoculars are better sealed
against dust, pollen, and
moisture than “external
focusing" binoculars. To tell
the difference, move the focus
wheel and see whether or not
the ocular bridge moves.
A very few superior binoculars
are waterproof (not “water
resistant," not “weather
resistant," not “splash proof").
They are waterproof – able to
withstand complete immersion
and remain dry inside. This is a
difficult (and expensive boast)
and binoculars that really are
waterproof/submersible will
certainly tout this.
You need not bird regularly in
pouring rain to appreciate the
benefits of well built, well sealed
optics.
The day you jump from your
air conditioned car into a
steamy Florida afternoon and
train your now completely
fogged binoculars upon the
swallow-tailed kite soaring
overhead will make you a
convert.
Other Important Considerations
Whether you are a World
Series of Birding combatant, a
rock climbing hawk watcher, or
a casual backyard birder who is
meticulously careful with
equipment – accidents do
happen. All birding binoculars
should be able to shrug off the
occasional bump and ding.
Superior binoculars are
impervious to airline baggage
handlers, children, and
tumbles onto pavement
precipitated by a combination
of motion, gravity, and a fall
to the roadway after being
left on the roof of a car.
Well constructed, well sealed,
armored binoculars offer
another advantage. They need
no special care – they don’t
even need to be returned to a
case after use! Hang them up
on the hook by the back door.
Put them under the front seat
of the car. They are there when
you need them. Ready at a
moment’s notice without having
to run to the closet...and grab
the box from it’s place on the
top shelf (out of the reach of
the kids)...and open the
case...and remove the
binoculars...and extract the
plastic plugs that protect the
lenses...and run back to the
kitchen window...to study the
vibrating branch where the bird
(that just left) had been
perched.
Lens protection is important,
so most manufacturers of
quality birding binoculars
include custom fitted rain
