3
Extending the Lens Shades
Another nice feature of the BT is its extendable lens shades
(Figure 1)
. These increase image contrast by preventing glare
(unwanted stray light) from entering the objective lenses of the bin-
oculars. They also slow the formation of dew on the objective lens
exteriors.
To use the lens shades, grasp them with your fingers, and pull them
outwards. You will need to retract the lens shades to fit the binoculars
into the box.
Adjusting the Distance
Between Your Eyes
(Interoccular Distance)
Adjusting the interoccular distance of the BT is incredibly easy.
Simply grasp the base sections below each eyepiece focuser hous-
ing
(Figure 1)
and rotate inwards or outwards with your thumbs.
The two housings are connected internally, so they rotate with each
other, always insuring the eyepieces stay level and aligned. Pivot the
bases while looking through the BT until the distance between the
eyepieces matches the distance between your eyes. When properly
adjusted, you should see a single, round field of view when looking
through the binoculars. Make this adjustment before you attempt to
focus the binoculars.
Focusing
The BTs utilize individual focus eyepieces. This makes the binoc-
ulars mechanically more rugged than similar center-focus models,
and generally maintains optical alignment better. For astronomical
observation, individual focus eyepieces are usually preferred.
Pick an object in the distance to view. At night, best focus will be
achieved by focusing on a medium bright star. Cover your right eye
(or cover the right objective lens of the binocular) and focus the left
eyepiece by rotating the rubber grip ring on the eyepiece holder until
the image appears sharp. Then cover your left eye (or cover the left
objective lens of the binocular) and focus the right eyepiece by rotat-
ing the eyepiece holder until the image appears sharp. The binoc-
ulars are now focused. If you want to view an object at a different
distance, re-focusing of both eyepieces is required. Also, changing
eyepieces may require refocusing.
For astronomical observation, all objects will always appear focused
at the infinity focus point. This means you only need to focus the
binoculars once per observing session per set of eyepieces. Since
everyone’s eyes focus images slightly differently, different observers
will need to refocus the binoculars for their own vision.
Waterproof Binoculars
The Orion BTs are sealed to be waterproof. While they are impervi-
ous to rain, wind, splashing, and humidity, do not immerse the binoc-
ular in water under any circumstances. If the binocular becomes wet
with fresh water, merely blot it dry with a clean cloth and clean the
lens surfaces as outlined below. Saltwater should be rinsed off com-
pletely and the binocular then blotted dry and its lenses cleaned as
outlined below. If the binocular body becomes dirty, it can be cleaned
with warm water and a clean cloth. If extremely dirty, or oily, clean the
body with a diluted solution of warm water and mild soap on a cloth,
then rinse with clean water and blot dry. Do not clean lens surfaces
with soap and water! The BTs are also not meant to be left outside
on a permanent basis. Exposure to the elements (especially UV sun-
light, and poor weather) will degrade the unit over time. Please bring
your BT inside when you are finished with your observing session.
Cleaning and Care of
Binocular Lenses
The lens surfaces of Orion binoculars are coated with anti-reflection
multi-coatings that can be damaged with careless handling. Avoid
touching lens surfaces with fingers or any coarse material. All optics,
even if stored, should be cleaned at least once a year or whenever
they are dirty. The dust that builds up on coatings promotes mold
growth, which etches glass and destroys coatings. Avoid over-clean-
ing; it can also damage the coatings. Always use lens cleaning tissue
and fluid that are specifically designed for multicoated lenses. Do not
use fluids or tissues that are for eyeglasses or household use. Never
attempt to disassemble the binocular or eyepieces in order to clean
them; this can also void the warranty.
To clean the binocular (and eyepiece) lenses, first blow off the lens
with a blower bulb or gently wipe the lens with a lens cleaning brush
to remove the larger particles. Put a few drops of lens cleaning fluid
on a fresh piece of lens cleaning tissue (never on the lens) and gen-
tly wipe the lens. Quickly wipe the excess fluid with a new, dry piece
of lens cleaning tissue. For larger lenses, clean only a small area at
a time, using a new tissue each time. On excessively dirty lenses,
wipe across the lens using one stroke for each tissue, alternating wet
and dry. Always avoid excessive pressure or rubbing when wiping, as
wiping too hard can scratch the lens.
Storage and Transport
The BTs come with a foam lined shipping box for safe storage and
transport. We recommend always keeping the binoculars in this box
with the cover caps on when not in use. Optional hard cases are
available if you want more protection for your Binocular Telescopes.
Model numbers for cases are as follows, please contact Orion for
purchase:
Case options:
Avoid unnecessary shocks to the binocular, whether it is in its box/
case or not. Although the BT is designed to be mechanically rugged,
excessive impacts may cause the optics to become misaligned. This
is not covered by the warranty.
Allow the optics to slowly adjust to cold weather by storing the instru-
ment in a cold area, such as an unheated garage or the trunk of a
car, for a few hours before use. When bringing the instrument back
inside a warm house, let everything dry out before placing the caps
• #51879:
BT-70 Case
• #51880:
BT-82 Case
• #51881:
BT-100 45º Case
• #51882:
BT-100 90º Case
