National Geographic Binoculars Owner's Manual - page 3
3) Turn the center focusing wheel of your binoculars until you have a clear view of your subject.
4)
Close your left eye and open your right eye. Do not readjust the center focusing wheel. Instead,
gently rotate the eyepiece first in one direction and then in the other until the subject appears
sharply in focus.
5) Now open both eyes. You should have a clear view of your subject and your eyes should not
feel strained.
For future use, you will have to adjust the center focusing wheel only to observe subjects,
regardless of distance.
NOTE: The right eyepiece has a scale with a plus sign, a minus sign, and a zero. Note that the
position of the indicator mark against this scale is your own personal setting. Use this as a
reference point if you need to realign your binoculars after somebody else has used them.
Binoculars that do not have a center focus wheel have eyepieces that focus individually. To focus
the right eyepiece, close your left eye and turn the right eyepiece until the image is sharp. Then
close your right eye and focus the left eyepiece in the same manner. Adjust as needed until you
have a perfectly focused image. Objects at varying distances will need to be refocused using the
proceeding technique.
Binocular features:
Fold-down rubber eyecups:
Most National Geographic binoculars have soft rubber eyecups to protect eyeglass lenses from
being scratched and to reduce the amount of distracting bright light reaching your eyes. If
sunglasses or eyeglasses hinder your view, simply fold down the rims of the rubber eyecups.
Return the rubber eyecups to their normal position when finished to reduce stress on the rubber
compound and to prevent the rubber from cracking. On the other models the eyecups are
extended or retracted by twisting them.
Optical lens multi-coatings:
The lenses and prisms of your National Geographic binoculars have been treated with the finest
quality coatings for better performance. The front lenses of many National Geographic binoculars
(the objective lenses) have been coated with as many as 12 layers of compounds that filter out
unwanted ultraviolet and infrared rays, increase light transmission, reduce out-of-phase light rays,
and enhance color purity and contrast. These quality coatings may give the lenses of your
National Geographic binoculars a distinctive green hue.
Long-eye relief:
The specially designed long-eye relief eyepieces allow you to see through your binoculars without
having to press them tightly against your eyes. This feature is especially convenient for eyeglass
wearers and is included in National Geographic models listed in the chart at the end of this
manual.
Rubber body armor: