ORION TELESCOPES & BINOCULARS 9969 User manual

INSTRUCTION MANUAL
IN 291 Rev. B 02/09
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Orion®180mm
Maksutov-Cassegrain
#9969 Optical Tube Assembly
Figure 1. The 180mm Maksutov-Cassegrain optical tube assembly.
Eyepiece
adapter
Dovetail holder
Meniscus lens
Mounting plate
Focus knob

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Getting Started
Your telescope comes fully assembled from the factory. The
optics have been installed and collimated, so you should not
have to make any adjustments to them. Keep the dust covers
on the telescope when it is not in use.
Please keep the original shipping box. In the unlikely event
you should need to ship the telescope back to Orion for war-
ranty repair service, you should use the original packaging.
The box also makes a very good container for storing the tele-
scope.
Mounting the Telescope
The dovetail mounting plate on the 180mm Maksutov-
Cassegrain is specifically designed to couple directly to the
SkyView Pro equatorial mount, which is an excellent mount
choice. Other equatorial and altazimuth mounts may require
removing the mounting plate so the tube can be attached with
tube rings.
Alternatively, the 180mm Mak-Cass optical tube assembly
can be mounted onto any standard camera tripod or mount
that has a 1/4"-20 mounting stud. The stud threads into one
of the holes on the underside of the mounting plate. There are
several threaded holes in the mounting plate; use the one that
will best balance the telescope on the tripod or mount.
Camera tripods or altazimuth mounts are desirable for ter-
restrial (land) viewing because they allow simple vertical and
horizontal movement of the telescope. An equatorial mount
is desirable for astronomical viewing because it allows easy
tracking of celestial objects as the Earth rotates. Also, the
setting circles on the equatorial mount enable you to locate
objects by their celestial coordinates (right ascension and
declination), which can be found in many observing books
and star atlases.
Use of Optional
Accessories
Your telescope does not come with any accessories so as to
offer the greatest flexibility in configuring it to your needs. If
you do not already own a 1.25" diagonal, a 1.25" eyepiece,
and a finder scope with dovetail bracket, you will need to pur-
chase these items separately. Consult the Orion catalog or
www.OrionTelescopes.com for these optional accessories.
The 180mm Maksutov-Cassegrain can use almost any
1.25" diagonal or eyepiece. To install a diagonal, unthread
the thumbscrews on the eyepiece adapter at the rear of the
tube and insert the diagonal. Secure it with the thumbscrews.
Then insert an eyepiece into the diagonal and secure it with
the thumbscrew(s) on the diagonal. The diagonal provides a
comfortable viewing angle and image orientation, while the
eyepiece is what actually magnifies the image produced by
the optical tube.
A finder scope is also required for easy aiming of the tele-
scope. The finder scope makes it easier to locate the sub-
ject you want to observe in the telescope, because the finder
scope has a much wider field of view. The dovetail holder on
the telescope’s tube is for a finder scope bracket. Any optional
Orion finder scope will come with a bracket that has a dovetail
base. The dovetail base goes into the dovetail holder, and is
secured with the thumbscrew on the holder.
Focusing
Point the telescope so the front end is aimed in the general
direction of an object you wish to view. When you first look in
the eyepiece, the image you see may be fuzzy, or out of focus.
If so, gently turn the focus knob with your fingers until the
image becomes sharp. Go a little bit beyond sharp focus until
the image just starts to blur again, then reverse the rotation
of the knob, just to make sure you’ve hit the exact focus point.
You will have to readjust the focus when aiming at subjects of
varying distances, or after changing eyepieces.
If you have trouble focusing, rotate the focus knob counter-
clockwise as far as it will go. Now look through the eyepiece
while slowly rotating the focus knob clockwise. You should
soon see the point at which focus is reached.
Do You Wear Eyeglasses?
If you wear eyeglasses, you may be able to keep them on
while you observe, if your eyepieces have enough “eye relief”
to allow you to see the whole field of view. You can find out by
looking through the eyepiece first with your glasses on and
then with them off, and see if the glasses restrict the view
to only a portion of the full field. If they do, you can easily
observe with your glasses off by just refocusing the telescope
the needed amount.
Welcome to a new world of adventure! Your new 180mm Maksutov-Cassegrain (Mak-Cass) telescope is
a fine-quality instrument designed for both daytime terrestrial viewing and nighttime stargazing. Compact,
portable, but with plenty of aperture, and easy to use, this versatile scope will provide many hours of
enjoyment for the whole family.
These instructions will help you set up and properly use and care for your telescope. Please read them
over thoroughly before getting started.
WARNING: Never look directly at the Sun through
your telescope—even for an instant—without a
professionally made solar filter that completely
covers the front of the instrument, or permanent
eye damage could result. Young children should use
this telescope only with adult supervision.

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If your eyes are astigmatic, however, images will probably
appear the best with glasses on.This is because a telescope’s
focuser can accommodate for nearsightedness or farsighted-
ness, but not astigmatism. If you have to wear your glasses
while observing and cannot see the entire field of view, you
may want to purchase additional eyepieces that have longer
eye relief.
Calculating Magnification
To calculate the magnification, or power, of a telescope with
an eyepiece, simply divide the focal length of the telescope by
the focal length of the eyepiece:
Telescope Focal Length (mm)
= Magnification
Eyepiece Focal Length (mm)
For example, the 180mm Maksutov-Cassegrain, which has a
focal length of 2700mm, used in combination with a 25mm
eyepiece, yields a magnification of:
2700 mm
= 108x
25 mm
It is desirable to have a range of eyepieces of different focal
lengths to allow viewing over a range of magnifications. It is
not uncommon for an observer to own five or more eyepieces.
Orion offers many different eyepieces of varying focal lengths,
so check the catalog or www.OrionTelescopes.com for a wide
selection of additional eyepieces to choose from.
Every telescope has a useful limit of power of about 2x per
millimeter of aperture (i.e. 360x for the 180mm Mak-Cass).
Claims of higher power by some telescope manufacturers are
a misleading advertising gimmick and should be dismissed.
Keep in mind that at higher powers, an image will always be
dimmer and less sharp (this is a fundamental law of optics).
The steadiness of the air (the “seeing”) can also limit how
much magnification an image can tolerate.
Always start viewing with your lowest-power (longest focal
length) eyepiece in the telescope. It’s best to begin observing
with the lowest-power eyepiece, because it will typically pro-
vide the widest true field of view, which will make finding and
centering objects much easier. After you have located and
centered an object, you can try switching to a higher-power
eyepiece to ferret out more detail, if atmospheric conditions
permit. If the image you see is not crisp and steady, reduce
the magnification by switching to a longer focal length eye-
piece. As a general rule, a small but well-resolved image will
show more detail and provide a more enjoyable view than a
dim and fuzzy, over-magnified image.
Terrestrial Viewing
For land viewing, it’s best to stick with low power eyepieces
that yield a magnification under 100x. At higher powers,
images rapidly lose sharpness and clarity due to “heat waves”
caused by Sun-heated air.
Remember to aim well clear of the Sun, unless the front of the
telescope is fitted with a professionally made solar filter and
the finder scope is covered with a completely opaque material
or removed altogether
Maksutov-Cassegrain telescopes are capable of focusing on
objects that are quite close, so you can view fine details of
objects that are nearby. Try focusing on a flower or insect at
close distance to enter a normally unseen microscopic world.
Astronomical Viewing
When choosing a location for nighttime stargazing, make it
as far away from city lights as possible. Light-polluted skies
greatly reduce what can be seen with the telescope. Also, give
your eyes at least 20 minutes to dark-adapt to the night sky.
You’ll be surprised at how many more stars you will see! Use
a red flashlight, to see what you’re doing at the telescope, or
to read star charts. Red light will not spoil your dark-adapted
night vision as readily as white light will.
To find celestial objects with your telescope, you first need
to become reasonably familiar with the night sky. Unless you
know how to recognize the constellation Orion, for instance,
you won’t have much luck locating the Orion Nebula. A simple
planisphere, or star wheel, can be a valuable tool for learning
the constellations and seeing which ones are visible in the
sky on a given night. A good star chart or atlas, like the Orion
DeepMap 600, can come in handy for helping locate interest-
ing objects among the dizzying multitude of stars overhead.
Except for the Moon and the brighter planets, it is pretty time-
consuming and frustrating to hunt for objects randomly, with-
out knowing where to look. It is best to have specific targets in
mind before you begin looking through the eyepiece.
Photography
When coupled to a 35mm single-lens reflex camera (or digital
equivalent), the 180mm Mak-Cass becomes a telephoto lens.
For terrestrial or astronomical photography, you need only
a T-ring for your specific camera model. The T-ring attaches
to your camera and threads onto the telescope’s eyepiece
adapter (see Figure 2).
Use the camera’s viewfinder to frame the picture. Use the
telescope’s focuser to focus the image. You may want to con-
sider using a remote shutter release instead of the shutter
release on the camera; touching the camera can vibrate the
system and blur the resulting photographic image. Also, be
sure to use a solid tripod.
Care & Maintenance
If you give your telescope reasonable care, it will last a life-
time. When not in use, keep the dust cover on the front of the
tube and the dust cap on the eyepiece adapter. Store it in a
clean, dry, dust-free place, safe from rapid changes in tem-
perature and humidity. Do not store the telescope outdoors,
although storage in a garage or shed is OK.
Your telescope requires very little mechanical mainte-
nance. The optical tube is aluminum and has a smooth

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Appendix: Collimating
Collimating is the process of aligning a telescope’s optics.Your
Maksutov-Cassegrain's primary mirror was aligned at the fac-
tory and should not need adjustment unless the telescope is
handled roughly. This manual contains information on how to
test the collimation of your telescope and instructions for prop-
er alignment should that be needed.
Star-Testing the Telescope
Before you start adjusting the primary mirror of your telescope,
make certain that it is actually out of collimation by performing
a star test.
Take your telescope out at dusk and let it acclimate to the out-
side temperature; this usually takes 30-60 minutes. When it is
dark, point the telescope upwards at a bright star and accu-
rately center it in the eyepiece’s field of view. Slowly de-focus
the image with the focusing knob. If the telescope is correctly
collimated, the expanding disk should be a circle (Figure 3).
If the image is unsymmetrical, the scope is out of collimation.
Also, the dark shadow cast by the secondary mirror should
appear in the very center of the out-of-focus circle, like the
hole in a donut. If the “hole” appears off-center, the telescope
is out of collimation.
If you try the star test but the bright star you have selected is
not accurately centered in the eyepiece, the optics will always
appear out of collimation, even though they may be perfectly
aligned. It is critical to keep the star centered, so over time you
will need to make slight corrections to the telescope’s position
in order to account for the sky’s apparent motion.
painted finish that is fairly scratch-resistant. If a scratch does
appear on the tube, it will not harm the telescope. If you wish,
you may apply some auto touch-up paint to the scratch.
Smudges on the tube can be wiped off with a soft cloth and
household cleaning fluid.
Any quality optical lens cleaning tissue and optical lens clean-
ing fluid specifically designed for multi-coated optics can be
used to clean the front meniscus lens of the telescope. Never
use regular glass cleaner or cleaning fluid designed for eye-
glasses. Before cleaning with fluid and tissue, however, blow
any loose particles off the lens with a blower bulb or com-
pressed air. Then apply some cleaning fluid to a tissue, never
directly on the optics. Wipe the lens gently, then remove any
excess fluid with a fresh lens tissue. Oily fingerprints and
smudges may be removed using this method. Use caution;
rubbing too hard may scratch the lens. For the large surface of
the meniscus lens, clean only a small area at a time, using a
fresh lens tissue on each area. Never reuse tissues.
Specifications
#9969 180mm Maksutov-Cassegrain OTA
Optical design: Maksutov-Cassegrain
Aperture: 180mm
Effective focal length: 2700mm
Focal ratio: f/15.0
Central obstruction diameter: 41mm
Primary mirror coating: Aluminum with SiO2 overcoat
Meniscus lens coating: Anti-reflection multi-coatings on both
sides of lens
Eyepiece adapter: Accepts 1.25" format accessories, camera
t-threads
Optical tube mounting plate: Fits all Orion EQ mounts equipped
with a dovetail tube mounting, and standard photo-style tri-
pods
Weight: 15.9 lbs
Figure 2.
A T-ring is all
that is needed to
connect a 35mm
SLR camera to
the telescope; it
threads onto the
eyepiece adapter
with eyepiece and
diagonal removed.
T-ring
Eyepiece
adapter
Figure 3. A star test will determine if a telescope’s optics are
properly collimated. An unfocused view of a bright star through the
eyepiece should appear as illustrated on right if optics are perfectly
collimated. If circle is unsymmetrical, as in illustration on left, scope
needs collimation.
Out of collimation Collimated

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Collimating
To collimate your telescope, remove the diagonal and eye-
piece and look into the rear opening of the tube (also remove
the dust cover from the front of the tube). This should be done
indoors, with the telescope pointed at a white wall in a well-
lit room. Try to keep your eye centered with respect to the
rear opening of the tube as best as possible. Using an Orion
Collimating Eyepiece will aid greatly in keeping your eye cen-
tered and is strongly recommended.
Alternatively, you can make a crude collimating tool out of an
empty, black plastic 35mm film canister. It will not have cross-
hairs, so it won’t be as precise, but it will be better than nothing.
Cut 1⁄2" from the top lip of the canister and put a 1/16" to 1/8"
diameter hole in the center of the canister’s bottom surface.
Insert the film canister collimating tool into the focuser like you
would an eyepiece with the bottom surface outward.
Once you are ready to collimate, look into the rear opening of
the tube. If your telescope is out of collimation, it will resemble
Figure 4a. You will see a reflection of the inside of the optical
tube resembling a black crescent. A properly collimated scope
will resemble Figure 4b. The direction of misalignment in your
telescope may differ from Figure 4a, but the diagram will give
you a general idea of how things will look.
Note there are three pairs of collimation screws on the back
of the optical tube (Figure 5). The tilt of the primary mirror is
adjusted with the three pairs of collimation screws. You will
need a 4mm and 2.5mm hex key to turn these screws.
Each pair of collimation screws work together to adjust the tilt
of the primary mirror. One screw pushes the mirror cell for-
ward, while the other screw pulls the mirror cell back. One
must be loosened and the other tightened by equal amounts
in order to adjust the tilt. Look into the rear opening of the tube
and locate the black crescent that indicates the optics are out
of collimation. Note which way the front of the telescope would
need to move in order to “fill” that black crescent and resem-
ble Figure 4b. Then look at the back end of the telescope and
locate the pair of collimation screws that are in the direction
that the front of the telescope needs to move. Tighten one of
these screws by one turn, and loosen the other screw of the
pair by one turn. Look into the rear opening of the tube and
determine if the black crescent has reduced in size, increased
in size, or been “filled.” If the crescent has reduced in size,
continue adjusting the pair of collimation screws in the same
manner until the crescent has been completely “filled.” If the
crescent has increased in size, the optics have been moved
further out of alignment. To correct this, loosen and tighten the
same pair of collimation screws by one turn to undo the previ-
ous adjustment. Then adjust the other two pairs of collimation
screws until the black crescent is “filled.”
Figure 5. The 180mm Maksutov-Cassegrain screws
Front of
telescope
Secondary
mirror Reflection of
your eye in
secondary
mirror
Secondary
reflection of
inside of tube
Reflection of
inside of tube
(misalignment)
Figure 4a
Figure 4a. If the telescope’s optics are out of alignment the view
through the rear opening of the telescope will resemble Figure-4a.
Figure 4b. With the optics properly aligned the view through the
rear opening of the telescope will resemble Figure 4b.
Front of
telescope
Secondary
mirror Reflection of
your eye in
secondary
mirror
Figure 4b
Collimation
screw pairs Rear
opening