Orion 9931 User manual

IN 049 0698
Providing Exceptional Consumer Optical Products Since 1975
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INSTRUCTION MANUAL
Orion®
Deep Space Explorer™
#9931, #9932, #9935 6", 8", & 10" Dobsonian Reflecting Telescopes

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To get the most out of your new telescope, take the time to
read this instruction manual thoroughly. The following sugges-
tions, in particular, should be heeded.
1. Never look directly at the Sun without a proper, profession-
ally made solar filter. Doing so could cause permanent eye
damage or even blindness. Never use a dark-glass screw-
in eyepiece filter; it may crack under intense heat.
2. Like all reflector telescopes, performance is best after the
telescope has cooled to the outdoor temperature for at
least an hour (longer in colder climates). If possible, store
the telescope in a cold place, such as a garage, to mini-
mize the cooling time. It’s best to observe with low powers
until the telescope has equilibrated.
3. Observe from a dark location, away from street and porch
lights. Your eyes take 10 to 30 minutes to adapt to the
darkness. Use a red-filtered flashlight to preserve your
dark-adapted night vision; a white light can greatly and
instantly reduce your low-light sensitivity.
4. Keep your telescope’s mirrors in good optical alignment
(collimation). The technique for collimation is easily
learned (see section 5). Although adjustment is required
only occasionally, performance is noticeably improved.
5. Never lubricate the bearing surfaces of your Dobsonian
telescope. Doing so reduces the bearing friction and
causes the telescope to move too freely. The inherent fric-
tion of the bearing surfaces is an important part of the
telescope design.
Congratulations on purchasing an Orion Deep Space Explorer reflector telescope! It is a precision
instrument designed exclusively for astronomical observation. With its sharp Newtonian optical system
and its easy-to-use Dobsonian mount, you'll enjoy countless views of fascinating celestial objects.
Saturn’s rings will inspire your imagination; Jupiter's moons and great cloud bands will amaze you. You’ll
see hundreds of mountains, craters, and other surface details as you explore the surface of our nearest
celestial neighbor, the Moon.
Your Deep Space Explorer is also particularly well suited for observing deep-space objects beyond our
solar system. From dark sky locations, you can observe glowing nebulas such as the Great Orion
Nebula, incredibly distant galaxies such as the Andromeda Galaxy, star clusters like the dazzling
Hercules Cluster, and planetary nebulas like the famous Ring Nebula.
If you have never used a telescope before, we would like to welcome you to amateur astronomy. Take
some time to familiarize yourself with the night sky. Learn to recognize the patterns of stars in the major
constellations; a star wheel, or planisphere, available from nature stores or astronomical suppliers, will
greatly help. With a little practice, a little patience, and a reasonably dark sky away from city lights, you’ll
find your telescope to be a never-ending source of wonder, exploration, and relaxation.
Table of Contents
1. Important Points About Your Telescope ............................................................................... 3
2. Terminology ......................................................................................................................... 4
3. Assembly ............................................................................................................................. 4
4. Using Your Telescope........................................................................................................... 5
5. Collimation of the Optics (Aligning the Mirrors)................................................................... 6
6. Observing Tips and Techniques .......................................................................................... 8
7. Astronomical Viewing........................................................................................................... 9
8. Enhancement, Care, and Maintenance ................................................................................ 11
9. Specifications........................................................................................................................ 13
1. Important Points About Your Telescope
WARNING: Never look directly at the Sun
through your telescope or its finder scope—
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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2. Terminology
Altitude Bearings The two round plastic protrusions on
opposite sides of the optical tube, which rest in the cradle of
the Dobsonian base. They allow the telescope to be pivoted
up or down (altitude).
Altitude Bearing Pads The pads of material on the Dobsonian
cradle where the optical tube side (altitude) bearings rest.
Azimuth Pads The white Teflon pads between the two base
plates, which allow the telescope to be moved side to side
(azimuth).
Azimuth Pivot Bolt The bolt through the center of the two
base plates, which serves as a pivot point for azimuthal rotation.
Collimation Alignment of the optical elements of an instru-
ment. Proper collimation is necessary to achieve peak optical
performance.
Ground Baseplate On the Dobsonian base, the round board
closest to the ground. It often has “feet” on the underside and
three azimuth bearing pads on the perimeter of its upper surface.
Dobsonian Mount A type of simple, cabinet-style altazimuth
mount for a Newtonian reflector, invented by John Dobson of
the San Francisco Sidewalk Astronomers club.
Eyepiece A lens-containing barrel that magnifies the image
formed by the telescope and allows your eye to focus on it.
Eyepieces of different focal lengths will produce different
magnification factors.
Finder Scope A small, low-power refracting telescope, usu-
ally with crosshairs, mounted on the optical tube of the main
telescope to aid in pointing the telescope. Its wide field of view
facilitates the location of target objects. When properly
aligned with the main telescope, an object centered in the
finder scope will also be centered in the main telescope’s
much narrower field of view.
Optical Tube The main body of the telescope, which houses
the optics.
Primary Mirror The large, concave mirror located at the back
end of the optical tube. It reflects incoming light to the second-
ary mirror near the front of the tube.
Primary Mirror Cell The mechanical holder for the primary
mirror. It features alignment-adjusting bolts (usually three)
that allow exact positioning of the tilt of the primary mirror.
Rack-and-Pinion Focuser A type of mechanical holder for
the eyepiece that enables the eyepiece to be moved in and out
to achieve sharp focus of the viewed image. It moves through
the interaction of a sawtoothed “rack” on the focuser drawtube
with a meshing “pinion” gear that is rotated with one’s fingers.
Secondary Mirror The small, elliptically shaped, flat mirror
located inside the optical tube beneath the focuser. Its func-
tion is to divert the light transmitted from the primary mirror
sideways into the focusing tube.
Secondary Mirror Cell The mechanical holder for the sec-
ondary mirror; usually a single stalk or an adjustable multivane
“spider.”
Top Baseplate On the Dobsonian base, the uppermost of the
two round boards, which rests atop the ground baseplate. It
supports the vertical struts of the telescope tube cradle. The
top baseplate rotates on the ground baseplate, allowing the
telescope to be moved in the azimuthal direction.
3. Assembly
Unpacking Your New Telescope
The telescope will arrive in two boxes, one containing the
telescope tube and optics, the other containing the unas-
sembled Dobsonian base and hardware. Exercise care when
unpacking the boxes. We recommend keeping the original
shipping containers; in the event that the telescope needs to
be shipped to another location or returned to Orion for war-
ranty repair, having the proper shipping containers will help
ensure that your telescope will survive the journey intact.
Assembly of the Dobsonian Base (Refer to Figure 1)
Before the telescope can be used, the base must be assem-
bled. This only has to be done once, unless you disassemble
the base for long term storage. The assembly process takes
about 15 minutes and requires only a Phillips screwdriver, the
large and small Allen wrenches provided, and two 1/2"
wrenches, or a combination of a wrench and pliers.
Note: When tightening screws, tighten them by hand until
firm, but be careful not to strip the holes by over-tightening. If
you use an electric screwdriver, do final tightening by hand.
C
C
B
D
A
F
I
H
E
G
Figure 1.

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1. Screw the rubber feet into the underside of the ground base-
plate (A) using the self-tapping wood screws provided, with
a Phillips screwdriver. Position the feet on the opposite side
of the ground baseplate from the preinstalled Teflon pads,
directly beneath them. To start the screw, hold it in position
and tap the head with the handle of the screwdriver.
2. Loosely attach the front brace (B) of the cradle to the two
sides (C) with four Allen-head screws in the predrilled
holes. Do not completely tighten the screws yet.
3. Attach the two sides (C) to the top baseplate (D) with the
remaining four Allen-head screws in the predrilled holes.
Tighten all four screws.
4. Tighten the four side screws installed earlier, and press on
the black plastic screw-head caps.
5. Insert the nylon bushing (E) into the hole in the center of
the top baseplate (D). Tap the nylon bushing in so it goes
all the way into the top baseplate and part way into the
ground baseplate (A). The nylon bushing should be flush
with the top surface of the top baseplate (D).
6. Place a nylon washer (F) over the long pivot bolt (G), then
insert the bolt up through the bottom of the ground base-
plate (A) and through the nylon bushing. Now thread on the
remaining nylon washer (H) and locking nut (I). Tighten the
locking nut just enough to allow a slight separation of the
top baseplate from the ground baseplate when the mount
is lifted. The purpose of the nut is to keep the two pieces
from coming apart when moving the telescope.
IMPORTANT! Overtightening the nut will make the mount dif-
ficult to rotate in the azimuthal direction.
7. Attach the handle to the front brace (B) with the two 1"
Allen screws provided in the predrilled holes. Place a
washer on each screw next to the screw head.
Installing the Primary Mirror
Leave the protective covering on the primary mirror until just
prior to installing it in the telescope tube. This is a first-surface
mirror and, while tough enough to survive years of use with-
out recoating, it is nevertheless delicate and must be handled
with extreme care. Do not touch the mirror’s aluminized top
surface with your fingers (or anything, for that matter)!
When you’re ready to install the mirror in the optical tube, fol-
low these steps:
1. Remove the protective tissue from the primary mirror. Set
the mirror cell on the floor in a clean room.
2. Carefully ease the tube over the mirror and mirror cell so
that the predrilled holes on the perimeter of the mirror cell
line up with the holes at the base of the optical tube.
3. With the 1" Allen-head bolts provided, secure the mirror
cell into place with the large Allen wrench.
4. You’ll adjust the alignment of the primary mirror later, in
Section 5.
Placing the Optical Tube on the Dobsonian Base
Lift the optical tube and set the altitude bearings on either
side of the tube in the “cradle” of the base, as shown. Once in
the cradle, the tube should pivot freely up and down with
gentle hand pressure. Note that the tube may not be properly
balanced yet, since the eyepiece and finder scope are not in
place. Proper balancing may require the use of an optional
counterweight system.
Installing the Finder Scope
We recommend mounting a finder scope to your Deep Space
Explorer to help in locating objects and centering them in the
main telescope’s field of view. The 5x finder scope included
with the DSE is easily attached with the two bolts and wash-
ers provided in the predrilled holes near the focuser (see
diagram). The holes are covered with small black caps, which
must be removed before installation of the finder scope.
Note that the finder scope bracket has a small cylindrical
“peep sight” in the stem. It is useful as a quick aiming device.
4. Using Your Telescope
Your Orion Deep Space Explorer Dobsonian telescope is one
of the easiest telescopes there is to use.You will be surprised
at the simplicity of operation, ease of manual tracking, and
exceptional optical performance. To get the most out of your
telescope, carefully read this section.
Transporting the Telescope
The telescope is easy to take wherever you want to do your
observing. There are only two pieces to deal with: the optical
Figure 2. The view down the focuser tube of a Newtonian
reflector with eyepiece removed. In this example, the optical
system is badly out of collimation.

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tube and the base. Don’t be afraid to load the telescope into
your car for a trip to the hills. Common sense prevails: as long
as the telescope does not bounce around, it won’t get dam-
aged in transit.
Naturally, you should be extra careful not to damage any
bearing surface, which could hinder the smooth movement of
the telescope.
Carry the telescope tube and the base separately (make two
trips). The handle on the Dobsonian base provides an easy
grip. While the two components are not terribly heavy, they
are bulky, so use caution to avoid hurting them or yourself. Be
especially careful when passing through doorways with the
optical tube: knocking it against the door frame doesn’t do the
optical alignment any good! It is always a good idea to get
someone to help you carry the telescope.
Set-Up and Field Use
When selecting a location for observing, get as far away as
possible from direct artificial light such as street lights, porch
lights, and automobile headlights. The glare from these lights
will greatly impair your dark-adapted night vision. The tele-
scope should be set up on a relatively level surface for proper
operation of the mount. A grass or dirt surface is preferable to
asphalt, because asphalt radiates more heat, which disturbs
the air and degrades the images.
It’s best also to escape the light-polluted city sky in favor of
dark country skies. You’ll be amazed at how many more stars
and faint deep-sky objects are visible in dark sky conditions.
Focusing the Telescope
Insert an eyepiece into the focuser and secure with the
thumbscrew. Look through the eyepiece and get a bright
object in the field of view. Now, with your fingers, slowly rotate
one of the focusing knobs until the object comes into sharp
focus. 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 hit the exact focus point.
If you have trouble focusing, aim the telescope at a bright
subject at least a few hundred feet away, such as a bright
light. Rotate the focuser fully clockwise so that the drawtube
is in as far as it will go. Now look through the eyepiece while
slowly rotating the focusing knob counterclockwise. You
should soon see the point at which focus is reached.
Aligning the Finder Scope
The finder scope and the telescope should be aligned to point
to exactly the same spot in the sky. Alignment is easiest to do
in daylight hours, before your observing session. Choose a
treetop, telephone pole, street sign-anything that is far off in
the distance, at least 200 yards away. Put that image in the
center of the field of your telescope’s eyepiece. Where is it in
your finder scope’s eyepiece? Hopefully, the image will be in
the field of view and some simple adjustments on the align-
ment screws of the mounting bracket will put the image
dead-center in the crosshairs.
By loosening one alignment screw and tightening another,
you can change the line of sight of the finder scope. Continue
making adjustments to the various alignment screws until the
image in both the finder scope the telescope’s eyepiece is
exactly centered. Check the alignment by moving the scope
Figure 3. Secondary mirror centered under focuser tube,
viewed through the collimating Eyepiece (as are the next
two illustrations).
Figure 4. Secondary mirror correctly aligned (tilted).

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to another object and fixing the crosshairs on the exact point
you want to look at. Then look through the telescope’s eye-
piece to see if that point is centered in the field of view. If it is,
the job is done. If not, make the necessary adjustments until
the two images match up.
5. Collimation of the Optics
(Aligning the Mirrors)
Collimation is the process of adjusting the mirrors so that they
are perfectly aligned with each other. Accurate alignment is
important to insuring the peak performance of your telescope
and should be done on a regular basis. Collimation is easy to
do and you should become familiar with the procedure, as
you will perform it often. Your telescope’s optics were aligned
at the factory, but may have jiggled out of alignment during
shipment or with rough handling. A simple star test will tell you
whether the optics are properly collimated.
Star-Testing Your Telescope
Point the telescope at a bright star and slowly rack the image
out of focus with the focusing knob. If the telescope is cor-
rectly collimated, the expanding disk should be a perfect
circle. If it is unsymmetrical, the scope is out of collimation. In
reflectors and Schmidt-Cassegrains, 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 doughnut. If the “hole”
appears off-center, the telescope is out of collimation.
Use a Collimation Tool
To aid in centering your line of sight down the focuser draw-
tube, and in centering the mirror reflections during collimation,
it is very helpful to use a precision collimating tool containing
crosshairs, such as the Orion Collimating Eyepiece #3640.
We highly recommend that you purchase one, as you will use
it for as long as you own this, or any, reflecting telescope.
Mechanically Centering the Mirrors in the
Optical Tube
With the telescope pointed away from the Sun, stand a couple
feet away from the front of the telescope and look down the
optical tube. Check that the secondary (or diagonal) mirror is
positioned in the center of the tube. Use a ruler if necessary
to measure the distance from the center of the secondary
mirror holder to the inside of the tube along each of the four
“spider” vanes; the distance should be the same along each
vane. The spider adjustment is set at the factory, so it will
probably be fine right out of the box.
Should you have to adjust the secondary mirror position, do
so by turning the Allen-head spider vane adjustment bolts on
the outside of the optical tube with the small Allen wrench
provided. Unthread one bolt a small increment while thread-
ing in the opposite bolt the same increment. Work with two
bolts at a time until the mirror is centered.
Now check that the primary mirror is centered in the optical
tube. There should be an equal amount of space between the
edge of the primary mirror and the inside of the optical tube
all the way around. A quick visual inspection usually suffices.
If the primary is obviously not centered, it will need to be
repositioned in its mirror cell.
Centering the Secondary Mirror Under the Focuser
If there is an eyepiece in the telescope, remove it. Look down
into the open focuser drawtube at the secondary (diagonal) mir-
ror. It should be centered in the field of view. You will see the
secondary mirror and mirror holder as well as reflections of the
secondary mirror and holder and the primary mirror, and your
eye. It’s pretty confusing, so refer to Figure 2 to sort them all out.
(This figure shows what you would see if both the primary and
secondary mirrors were out of alignment and the secondary
mirror were not centered below the focuser tube.)
If the secondary mirror is not in the center of the focuser draw-
tube, it must be adjusted. It really helps to put a piece of white
paper on the inside of the optical tube opposite the focuser.
The white paper forms a bright background behind the sec-
ondary mirror as you look down the focuser drawtube, making
it easier to distinguish the mirror holder from the background.
The secondary mirror is moved forward and back on a thread-
ed rod that extends from the secondary mirror into the
four-vane spider center support. The threaded rod has nuts
on both sides of the spider to hold it in place. By threading the
two nuts in one direction or the other, you can move the rod
forward or back to correctly center the secondary mirror under
the focuser. When you’ve achieved the correct position
(Figure 3), make sure the two nuts are threaded against the
spider center support to hold the rod securely in place.
Adjusting the Tilt of the Secondary Mirror
Look in the focuser drawtube and see if the entire reflection
of the primary mirror is visible and precisely centered in the
secondary mirror. It’s centered if there is an even ring of
space between the reflection and the edge of the secondary
mirror (Figure 4). If there is not, you will need to adjust the tilt
of the secondary mirror. (It helps to adjust the secondary mir-
ror in a brightly lit room with the telescope pointed toward a
bright white surface, such as white paper or a wall.)
First, loosen the four Allen-head alignment screws in the sec-
ondary mirror holder enough to be able to rotate the holder
with your hand. Now look into the focuser and rotate the sec-
ondary mirror holder slightly one way, then the other, with
your hand, until the reflection of the primary mirror is as cen-
tered in the secondary mirror as it will get. It still may not be
perfectly centered yet, but that is OK. Now secure the holder
in that rotational position by threading the four alignment
screws back in.
Now, if the entire primary mirror reflection still is not visible
and centered in the secondary mirror, adjust the secondary
mirror tilt further by alternately loosening one of the four align-
ment screws and tightening the opposite one a turn or so.
Remember, the goal is to center the primary mirror reflection
in the secondary mirror, as depicted in Figure 4. Don’t worry
that the reflection of the secondary mirror (the smallest circle

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with your eye in it) and spider are off-center (as also is the
case in Figure 4); you will fix that in the next step.
Adjusting the Tilt of the Primary Mirror
The final adjustment is made to the primary mirror. It will need
adjustment if, as in Figure 4, the secondary mirror is centered
under the focuser and the reflection of the primary mirror is
centered in the secondary mirror, but the small reflection of
the secondary mirror (with your eye inside) is off-center.
The tilt of the primary is adjusted with the three Allen-head
collimation bolts at the bottom of the optical tube, behind the
primary mirror. With the large Allen wrench provided, turn one
bolt at time, no more than one turn at a time, then look into
the focuser again and see if the secondary mirror reflection
has moved closer to the center of the primary mirror reflec-
tion. You will soon get a feel for which bolts to turn in which
direction and how far, until finally the secondary mirror reflec-
tion is dead center. (It helps to have two people for primary
mirror collimation, one to look in the focuser while the other
adjusts the collimation bolts.)
The collimation bolts are spring-loaded, so once you achieve
the correct mirror tilt, just leave the bolts as they are; the mir-
ror will remain in the adjusted position.
The view through the Collimating Eyepiece should now
resemble Figure 5. The secondary mirror is centered in the
focuser; the reflection of the primary mirror is centered in the
secondary mirror, and the reflection of the secondary mirror
is centered in the reflection of the primary mirror.
Your telescope is in precise collimation—optically primed for
peak performance! Once again, confirm the collimation by
conducting a star test.
6. Observing Tips &
Techniques
Pick a location away from street lights and bright yard lighting.
Avoid viewing over rooftops and chimneys, as they often have
warm air currents rising from them, which distorts the image
seen in the eyepiece. Similarly, you should not observe
through an open window from indoors.
“Seeing” and Transparency
Atmospheric conditions vary significantly from night to night.
“Seeing” refers to the steadiness of the Earth’s atmosphere at
a given time. In conditions of poor seeing, atmospheric turbu-
lence causes objects viewed through the telescope to “boil.”
If, when you look up at the sky with just your eyes, the stars
are twinkling noticeably, seeing is bad and you will be limited
to viewing with low powers (bad seeing affects images at high
powers more severely). Planetary observing may also be
poor. Make sure you are not looking over buildings or any
other source of heat; that will also cause image degradation.
In conditions of good seeing, star twinkling is minimal and
images appear steady in the eyepiece. Seeing is best over-
head, worst at the horizon. Also, seeing generally gets better
after midnight, when much of the heat absorbed by the Earth
during the day has radiated off into space.
Especially important for observing faint objects is good transpar-
ency—air free of moisture, smoke, and dust. All tend to scatter
light, which reduces an object’s brightness. Transparency is
judged by the magnitude of the faintest stars you can see with the
unaided eye (6th magnitude or fainter is desirable).
Cooling the Telescope
All optical instruments need time to reach “thermal equilibri-
um” to achieve maximum stability of the lenses and mirrors,
which is essential for peak performance. When moved from a
warm indoor location into the cooler outdoor air, a telescope
needs time to cool to the outdoor temperature. The bigger the
instrument and the larger the temperature change, the more
time is needed.
For your DSE, allow at least one hour for it to equilibrate. If the
scope has to adjust to more than a 40° temperature change,
allow two to four hours. In the winter, storing the telescope
outdoors in a shed or garage greatly reduces the amount of
time needed for the optics to stabilize.
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 try this 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.
Figure 5. Primary mirror correctly aligned. The telescope’s
optical system is now collimated.

8
Let Your Eyes Dark-Adapt
Do not expect to go from a lighted house into the darkness of
the outdoors at night and immediately see faint nebulas, gal-
axies, and star clusters-or even very many stars, for that
matter. Your eyes take about 30 minutes to reach perhaps
80% of their full dark-adapted sensitivity. Many observers
notice improvements after several hours of total darkness. As
your eyes become dark-adapted, more stars will glimmer into
view and you’ll be able to see fainter details in objects you
view in your telescope. Exposing your eyes to very bright
daylight for extended periods of time can adversely affect your
night vision for days. So give yourself at least a little while to
get used to the dark before you begin observing.
To see what you’re doing in the darkness, use a red-filtered
flashlight rather than a white light. Red light does not spoil
your eyes’ dark adaptation like white light does. A flashlight
with a red LED light is ideal, or you can cover the front of a
regular incandescent flashlight with red cellophane or paper.
Beware, too, that nearby porch and street lights and automo-
bile headlights will ruin your night vision.
Eyepiece Selection
Always start viewing with your lowest-power, widest-field eye-
piece. After you have located and looked at the object with a
low-power eyepiece, switch to a higher-power eyepiece and
see if the object looks better or worse. Keep in mind that at
higher power, an image will always be fainter and less sharp
(this is a fundamental law of optics). Many viewers use the
lowest-power eyepiece practically all the time! Naturally,
higher magnifications are desirable for viewing some celestial
objects, but stay with low powers when searching for an
object and for extended viewing.
To calculate the power, or magnification of a telescope, divide the
focal length of the telescope by the focal length of the eyepiece.
Telescope focal length ÷ Eyepiece focal length =
Magnification
For example, if you are using an Orion 6" DSE, which has a
focal length of 1200mm, and a 25mm eyepiece, the power
would be
1200 ÷ 25 = 48x.
We recommend having a selection of three to six eyepieces
of different focal lengths, so that you can choose the optimal
magnification, brightness level, and contrast for each object
and for different observing conditions.
Some exotic, extra-heavy eyepieces may cause enough
imbalance on the tube that you will need to adjust the coun-
terweight for optimum telescope balance.
7. Astronomical Viewing
How to Find Interesting Celestial Objects
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 will not 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 can come in very handy for helping
find 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,
without knowing where to look. You should have specific tar-
gets in mind before you begin looking through the eyepiece.
Start with a basic star atlas, one that shows stars no fainter
than 5th or 6th magnitude. In addition to stars, the atlas will
show the positions of a number of interesting deep-sky
objects, with different symbols representing the different
types of objects, such as galaxies, open star clusters, globu-
lar clusters, diffuse nebulas, and planetary nebulas. So, for
example, your atlas might show that there is a globular cluster
sitting just above the lid of the “Teapot” pattern of stars in
Sagittarius. You then know to point your telescope in that
direction to home in on the cluster, which happens to be
6.9-magnitude Messier 28.
The Moon
Viewing of the Moon, with its rocky, cratered surface, is one of
the easiest and most interesting ways to use your telescope.
The best time to observe our one and only natural satellite is
during a partial phase, that is, when the Moon is not full.
During partial phases shadows on the surface reveal more
detail, especially right along the border between the dark and
light portions of the disk. A full Moon is too bright and devoid
of surface shadows to yield a pleasing view.
The Planets
The planets don’t stay put like the stars, so you will have to
refer to charts published monthly in Astronomy, Sky &
Telescope, or other astronomy magazines to locate them.
Venus, Mars, Jupiter, and Saturn are the brightest objects in
the sky after the Sun and the Moon. Your Deep Space
Explorer is capable of showing you these planets in some
detail. Other planets may be visible but will likely appear star-
like. Because planets are quite small in apparent size,
optional higher-power eyepieces are recommended and often
needed for detailed observations. Not all the planets are gen-
erally visible at any one time.
JUPITER The largest planet, Jupiter, is a great subject for the
Deep Space Explorer. You can see the disk of the giant planet
and watch the ever-changing positions of its four largest moons-
Io, Callisto, Europa, and Ganymede. Higher-power eyepieces
should bring out the cloud bands on the planet’s disk.
SATURN The ringed planet is a breathtaking sight when it is
well positioned. The tilt angle of the rings varies over a period
of many years; sometimes they are seen edge-on, while at
other times they are broadside and look like giant “ears” on
each side of Saturn’s disk. A steady atmosphere (good see-
ing) is necessary for a good view. You will probably see a
bright “star” close by, which is Saturn’s brightest moon, Titan.
VENUS At its brightest, Venus is the most luminous object in
the sky, excluding the Sun and the Moon. It is so bright that

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sometimes it is visible to the naked eye during full daylight!
Ironically, Venus appears as a thin crescent, not a full disk,
when at its peak brightness. Because it is so close to the Sun,
it never wanders too far from the morning or evening horizon.
No surface markings can be seen on Venus, which is always
shrouded in dense clouds.
MARS The Red Planet makes its closest approach to Earth
every two years. During close approaches you’ll see a red
disk, and may be able to see the polar ice cap. To see surface
detail on Mars, you will need a high-power eyepiece and very
steady air!
The Stars
Stars will appear like twinkling points of light. Even powerful
telescopes cannot magnify stars to appear as more than a
point of light! You can, however, enjoy the different colors of
the stars and locate many pretty double and multiple stars.
The famous “Double-Double” in the constellation Lyra and the
gorgeous two-color double star Albireo in Cygnus are favor-
ites. Defocusing a star slightly can help bring out its color.
Deep-Sky Objects
Under dark skies, you can observe a wealth of fascinating deep-
sky objects, including gaseous nebulas, open and globular star
clusters, and a variety of different types of galaxies. Most deep-
sky objects are very faint, so it is important that you find an
observing site well away from light pollution. Take plenty of time
to let your eyes adjust to the darkness. Do not expect these
subjects to appear like the photographs you see in books and
magazines; most will look like dim gray smudges. (Our eyes are
not sensitive enough to see color in deep-sky objects except in
few of the brightest ones.) But as you become more experi-
enced and your observing skills get sharper, you will be able to
ferret out more and more subtle details.
Consult a star atlas or deep-sky observing guide for informa-
tion on finding and identifying deep-sky objects. Some good
sources to start with are the Edmund Mag 6 Star Atlas, Turn
Left at Orion, and The Universe From Your Backyard.
8. Enhancement, Care,
and Maintenance
Installation of Optional Finder Scope
Your telescope comes from the factory with holes pre-drilled
for the Orion 5x finder scope.
To install other finder scope models, you will need to drill the
holes yourself. Choose a position for the finder scope that is
directly on top of the telescope tube, near the focuser, when
the tube is aimed at the horizon. When drilling holes, be care-
ful not to let dust fall onto the mirrors. You may want to cover
the secondary mirror with a plastic bag while you are install-
ing a finder scope.
Use a black marker or black paint to coat the silver heads of
the screws and washers if you do not use blackened screws.
The additional weight of a finder scope may cause the tube to
be out of balance. If this occurs, you will need to attach a small
counterweight to the bottom of the tube near the primary mirror.
Balancing the tube is discussed in section 4 of this manual.
Important Note: Keep the tube in a horizontal position when
working with tools or hardware so that dust, dropped screws,
or tools cannot fall on the optical surfaces of the primary or
secondary mirrors!
Care of the Tube & Base
Give your telescope reasonable care and it will last a lifetime.
Store it indoors or in a dry garage. Do not leave it exposed
outside except when using it. When the telescope is not in
use, keep it covered with a plastic tarp or drop cloth or an
Orion Scope Saver to keep dust and dirt off.
An important design characteristic of your telescope is the
controlled friction of the bearing surface materials. To pre-
serve the optimum friction, never lubricate the bearings! Oil,
wax, grease, silicone, or graphite will greatly impair the
mechanical performance of the telescope, as the tube will
swing wildly at the slightest touch. Simply keep the bearing
surfaces clean with a dry cloth. Any household spray cleaner
will work fine to clean any foreign material or oil from the sur-
faces. The base is made of cabinet-grade “Melamine”
laminate, and will take quite a bit of wear and tear.
The optical tube is a “Sonotube,” a thick spiral-wound paper
bonded with waterproof glue. Sonotubes are used for pouring
concrete columns, so they are very strong. The material is
quite stable even with variation in humidity. Sonotubes are far
and away the most popular tubes for Dobsonian telescopes.
Transporting your Deep Space Explorer
When transporting your telescope, separate the base from
the tube and put the tube on a soft surface (back seat, blan-
ket, etc.) to keep it from getting banged around.
When shipping your DSE, should you have to, you must pro-
tect the first-surface primary mirror.
1. Remove the primary mirror cell and mirror from the tele-
scope tube assembly.
2. Blow any dust or particles from the mirror. It is best to use
a blower bulb. Do not use canned air or hair dryers.
Blowing with your breath is better than not doing anything.
3. Protect the surface of the mirror. Do not touch it. The mir-
ror MUST be covered with a soft, nonabrasive material. In
order of preference: original tissue wrap, lots of lens clean-
ing tissue, a clean 100% cotton cloth or shirt, facial tissue,
or toilet paper.
4. Pack the mirror assembly and telescope well. Always use
the original packing material if possible. If not, you should
“double box” the mirror assembly to ensure adequate pro-
tection.
Care of the Optics
Any quality optical lens cleaning tissue and optical lens clean-
ing fluid specifically designed for multi-coated optics can be
used to clean the exposed lenses of your eyepieces or finder

10
scope. Never use regular glass cleaner or cleaning fluid
designed for eyeglasses. Always apply the fluid to the tissue,
never directly on the optics. Gently wipe the lens, taking care
not to rub too hard. Use lots of tissue on larger lenses. DO
NOT take eyepieces apart for cleaning!
Cleaning First-Surface Mirrors
Cleaning is seldom needed (perhaps once a year) and best
done only when definitely needed. Covering your telescope
will prevent the mirrors from getting dirty. Improper cleaning
can scratch mirror coatings, so don’t be too eager to do so.
Small specks of dust or flecks of paint have virtually no affect
on performance, so do not clean your mirror too often. It is too
much trouble for little gain!
The primary mirror and secondary mirror of your telescope
are front-surface aluminized and then overcoated with hard
silicon monoxide, which prevents the aluminum from oxidiz-
ing. These coatings normally last through many, many years
of use before requiring recoating (which is easily done).
The diagonal mirror is more likely to require cleaning, since it
is right up near the eyepiece. It should be cleaned by blowing
dust off first, then wiping gently with cleaning tissue damp-
ened with lens fluid. Be extra gentle when cleaning first-surface
mirrors; be especially careful not to rub grit over the surface.
Very tiny, barely visible “sleeks” are not unusual and don’t
affect performance. A sleek will only be visible when looking
from an angle at the mirror, while a scratch will be visible all
the time.
A primary mirror does not need to be spotless to function
properly. The light-gathering surface of the mirror vastly
exceeds the surface area of dust particles that may accumu-
late. When you notice dust particles on the surface of the
mirror, they may be blown off using a blower bulb. However,
there will come a time when the primary mirror will need to be
cleaned; this should be done with care.
Distilled water can be used to cleanse the mirror. Over a sink,
rinse the mirror cell assembly with the distilled water. Hold the
mirror cell assembly at a steep angle so the water will run off
the surface of the mirror. If necessary, dirt and grease smudg-
es can be removed with a wet cotton ball. Use one cotton ball
for every wipe of the mirror.
For a really dirty mirror, or every three to five years, a more
thorough cleaning of the mirror can be undertaken. The mirror
must be separated from the mirror cell assembly: remove the
safety tape wrapping and carefully cut the silicone glue which
holds the mirror to the particle board baking plate. Take extra
precautions not to scratch the mirror during this step.
Fill a dish tub or sink with a gallon of distilled water, add 10
drops of Ivory liquid soap or lens cleaning solution that is safe
for multi-coated eyepieces. Soak the mirror, aluminized side
up, for about 10 minutes. Then, with the mirror still under
water, use a cotton ball and gently wipe the mirror. Wipe in
one direction only, and after each wipe discard the cotton ball
and use a fresh one for the next wipe. After the mirror is clean,
rinse with distilled water. Hold the mirror at a steep angle and
use a blower bulb to help the water droplets drain from the
surface; a cotton ball can be used to soak up some of the
excess water. Air dry.
Once dry, clean any remaining silicone from both the back of the
mirror and the particle board backing plate. Use silicone glue (clear
silicone caulking works well) to reattach the mirror to the backing
plate. The mirror cell assembly is now ready to be reinstalled.
With very little maintenance, your Orion Deep Space Explorer
will provide years of viewing pleasure.
Enjoy the view!
9. Specifications
6" DSE
Primary mirror focal length: 1200mm
Primary mirror diameter: 6 inches
Focal ratio: f/8
Weight: 33 lbs. (base 18 lbs., tube assembly 15 lbs.)
Tube length: 50 inches
Power with standard 25mm eyepiece (1.25"): 48x
8" DSE
Primary mirror focal length: 1200mm
Primary mirror diameter: 8 inches
Focal ratio: f/6
Weight: 41 lbs. (base 21 lbs., tube assembly 20 lbs.)
Tube length: 51 inches
Power with standard 25mm eyepiece (1.25"): 48x
10" DSE
Primary mirror focal length: 1140mm
Primary mirror diameter: 10 inches
Focal ratio: f/4.5
Weight: 68 lbs. (base 30 lbs., tube assembly 38 lbs.)
Tube length: 50 inches
Power with standard 25mm eyepiece (1.25"): 46x