Orion 23013, 23016, 23017, 23019, 23020 Instruction Manual

INSTRUCTION MANUAL

Orion® Premium

Deep Space Explorer

10" & 12.5"

#23013, #23016, #23017, #23019, #23020, #23022

Dobsonian Reflecting Telescope

™

Providing Exceptional Consumer Optical Products Since 1975

10"DSE

12.5" DSE

2" Low Profile

Focuser

#23013

NA

1.25" Rack & Pinion
Focuser

Customer Support [phone]
E-mail: [e-mail]

Corporate Offices [phone]

P.O. Box 1815, Santa Cruz, CA 95061

#23022

NA

2" Rack & Pinion

Focuser

#23019

#23020

2" Crayford

Focuser

#23016

#23017

IN 055 Rev B 0199

Congratulations on purchasing an Orion Premium Deep Space Explorer telescope! It is a precision

instrument designed exclusively for astronomical observation. With its enhanced Newtonian optical sys­tem and its easy-to-use Dobsonian mount, you’ll enjoy countless views of fascinating celestial objects.

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. 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 ............................................................................... 2

2. Terminology ......................................................................................................................... 2

3. Assembly ............................................................................................................................. 3

4. Using Your Telescope ........................................................................................................... 4

5. Collimation of the Optics (Aligning the Mirrors) ................................................................... 6

6. Observing Tips and Techniques .......................................................................................... 8

7. Astronomical Viewing ........................................................................................................... 9

8. Care and Maintenance ...................................................................................................... 10

9. Specifications ....................................................................................................................... 11

1. Important Points About
Your Telescope

To get the most out of your new telescope, take the time to read
this instruction manual thoroughly. The following suggestions, in
particular, should be heeded.

1. Never look directly at the Sun without a proper, professionally
made solar filter. Doing so could cause permanent eye dam­age or even blindness. Never use a dark-glass solar filter that
threads into an eyepiece; it may crack under the intense heat
that builds up at the focal plane.

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 minimize 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). Adjustment is required only occasionally, and
performance will be 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 friction of the bearing
surfaces is an important part of the telescope design.

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.

2. Terminology

Altitude Bearings The two round hubs 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 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 instrument.

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.

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Ebony Star Pebbly Formica surface on the azimuth axis on

which the Teflon pads make contact, providing buttery smooth
movement.

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 highly recommended optional accessory. It is a

small, low-power refracting telescope, usually with crosshairs, which
mounts 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.

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.

Optical Tube The main body of the telescope, which houses the

optics.

Optical Tube Handles Premium Deep Space Explorers come

with two handles to assist in lifting the optical tube onto and off of
the Dobsonian cradle. The handles are attached to the altitude
bearings on opposite sides of the optical tube.

Primary Mirror The large, concave mirror located at the back

end of the optical tube. It reflects incoming light to the secondary
mirror near the front of the tube.

Primary Mirror Cell The mechanical holder for the primary mir-

ror. It features alignment-adjusting bolts (usually three) that allow
exact positioning of the tilt of the primary mirror.

Secondary Mirror The small, elliptically shaped, flat mirror

located inside the optical tube beneath the focuser. Its function is to
divert the light transmitted from the primary mirror sideways into the
focusing tube.

Secondary Mirror Holder 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 is packaged in three boxes, one containing the
telescope tube, another containing the optics, and the other con­taining the unassembled 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 war­ranty repair, having the proper shipping containers will help
ensure that your telescope will survive the journey intact.

Parts List

Qty. Description

1 Optical Tube

1 Primary Mirror Cell

1 Ground Baseplate

1 Top Baseplate

2 Cradle Sides

1 Cradle Front Brace

8 Wood Screws (socket-head)

4 Black Plastic Screw-head Caps

1 Azimuth Pivot Bolt

1 Cylindrical Nylon Bushing

1 Locking Nut

2 Nylon Washers

3 Wood Feet

3 Self-tapping Wood Screws (Phillips-head)

2 Optical Tube Handles

1 26mm Sirius Plössl Eyepiece (1.25" barrel diameter)

4 Primary Mirror Cell Mounting Bolts (socket-head)

2 Allen Wrenches

Assembly of the Dobsonian Base

Before the telescope can be used, the base must be assembled
(refer to Figure 1, page 11). This has to be done only once,
unless you disassemble the base for long term storage. The
assembly process takes about 15 minutes and requires a Phillips
screwdriver, the Allen (hex) wrench provided, and two 1/2" cres­cent wrenches, or a combination of a common wrench, crescent
wrench, or pliers.

Note: When tightening screws, tighten them by hand until firm,
but be careful not to strip the holes by overtightening. If you use
an electric screwdriver, do final tightening by hand.

1. Screw the wood feet into the underside of the ground base­plate (A) using the self-tapping wood screws provided, with a
Phillips screwdriver. Position the feet on the underside of the
ground baseplate from the preinstalled Teflon pads, directly
beneath them.

2. Loosely attach the front brace (B) of the cradle to the two
sides (C) with four of the eight socket-head wood screws in
the predrilled holes, using the large Allen wrench provided.
Do not completely tighten the screws yet.

3. Attach the two sides (C) to the top baseplate (D) with the
remaining four socket-head wood screws in the predrilled
holes. Tighten all four screws.

4. Tighten the four side screws installed in step 2, then 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 bushing so it goes all the way into
the top baseplate and part way into the ground baseplate (A).
The bushing should be flush with the top surface of the top
baseplate (D).

3

6. Place a nylon washer (F) over the long pivot bolt (G), then
insert the bolt up through the bottom of the ground baseplate
(A) and through the nylon bushing. Now put on the remaining
nylon washer (H) and the locking nut (I). Tighten the 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 only to keep the two pieces from coming apart when
moving the telescope.

IMPORTANT! Overtightening the nut will make the mount
difficult to rotate in the azimuthal direction.

Installing the Optical Tube Handles

Premium Deep Space Explorers come with convenient handles
to help in lifting the optical tube onto and off of the Dobsonian
cradle. They also serve as levers for turning the telescope on the
azimuthal axis when the scope is pointed near the zenith (straight
overhead).

The handles attach to the altitude bearings (disks) on opposite
sides of the optical tube (refer to Figure 2). The handles should
be mounted in the center position on each of the bearings. Using
the provided Allen wrench, remove the bolt that resides in the
center hole.

To connect the handles to the altitude bearings, first remove the
nut and washer that is on the threaded shaft of each handle.
Insert the threaded shaft into the center hole in the altitude bear­ing. Rotate the handle clockwise until the shaft threads all the
way into the hole. Now, re-attach the nut and washer to the end
of the threaded shaft from the inside of the telescope. This will
require reaching up into the optical tube. This is easiest to do if
the telescope is resting on its side. Use a crescent wrench to
tighten the nut firmly.

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 without recoating,
it nevertheless must be handled with extreme care. Do not touch
the mirror’s aluminized surface or allow dirt and dust to build up on
it, as this could scratch the coating and compromise the optical
performance.

When you’re ready to install the mirror in the optical tube, follow
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 socket-head mounting bolts and the large Allen
wrench provided, secure the mirror cell into place.

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 by the handles on the altitude bearings and set
the tube down so the bearings rest in the “cradle” of the base, as
shown in the front cover picture. For the larger models, we recom­mend getting a friend to help lift the optical tube. Once in the
cradle, the tube should pivot freely up and down with gentle hand

pressure. Note that the tube may not be precisely balanced yet,
however, since the eyepiece is not in place. Proper balancing may
require the use of an optional counterweight system.

4. Using Your Telescope

Your Orion Premium 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, read this section carefully.

Use a Finder Scope

An optional finder scope is highly recommended to assist in aim­ing the telescope. It will help in locating objects and centering
them in the main telescope’s field of view. An 8x50 finder scope
or larger is recommended.

Your Premium DSE comes with two predrilled holes for an Orion
8x50 or 9x60 finder scope bracket. The holes are located a few
inches from the focuser. If you purchased an optional finder scope,
you will want to install it before using your telescope.

Hardware is not provided for attaching the finder scope since the
user could decide to put one of many different finder scopes onto
the Premium Deep Space Explorer, each of which might require
different nuts and bolts. For the Orion 8x50 or 9x60 finder scopes,
we recommend using 10-24 x 1" slotted machine screws and the
corresponding nut, accompanied with washers, to fasten the finder
to the main telescope. These items are available from any hardware
store. To minimize stray reflections, you can mount the finder scope
with the screws inserted from the inside of the tube out.

To install other finder scope models, you will need to drill the holes
yourself. Choose a position for the finder scope which is directly on
top of the telescope tube when the tube is aimed at the horizon, near
the focuser. Position the telescope tube so that it is lying horizontally,
parallel to the ground. Mark the spots for drilling mounting holes. Drill
holes the same size as the bolts being used. Be careful not to let
dust or debris fall onto the mirrors. You may want to cover the sec­ondary mirror with a soft tissue or a plastic bag while you are
installing the finder scope.

Aligning a 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 alignment 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 to another
object and fixing the crosshairs on the exact point you want to
look at. Then look through the telescope’s eyepiece to see if that

4

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.

Finder scopes often come out of alignment during transportation
of the telescope from site to site, so check the alignment before
each observing session. One way to help minimize any misalign­ment is to keep the bolts that attach the finder scope bracket to
the main telescope tube very tight.

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 tube and the

C

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 doesn’t
bounce around, it won’t get damaged 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. For the 12.5"
model you will need a second person to assist you in lifting and car­rying the individual components. Be especially careful when passing
through doorways with the optical tube: knocking it against the door
frame doesn’t do the mirror alignment any good!

B

I

H

E

D

A

F

G

Figure 1. Premium DSE Base Assembly

C

Focuser

Top Bolt

Center Hole

Figure 2. Installation of Tube Handles

Figure 3. Primary and Secondary Mirror Collimation Points

5

Set-Up and Field Use

When selecting a location for observing, get as far away as pos­sible from direct artificial light such as streetlights, porch lights, and
automobile headlights. The glare from these lights will greatly
impair your dark-adapted night vision. The telescope 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 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.

Balancing the Optical Tube

Your telescope was balanced at the factory for the standard
26mm Plössl eyepiece and an optional 8x50 finder scope. Adding
a different finder scope or an eyepiece of unusual weight to your
telescope may affect its balance. If the scope moves by itself
when you let go of the tube, you need to adjust the balance.

One possible source of imbalance is the position of the primary
mirror itself. Within limits, the entire primary mirror can be moved
up or down in the tube by tightening or loosening all of its align­ment screws. This also will have the effect of moving the focal
point of the telescope. Be sure you can still focus with all of your
eyepieces.

In the event that repositioning the mirror did not cure the imbalance,
an additional counterweight should be added to the telescope tube.
Any heavy object that will stay on the tube can provide the needed
ballast. Large metal washers hanging from a bolt or hook at the base
of the optical tube will often do the trick. Or a fishing weight. Your
Premium DSE has a 1/4"-20 threaded hole at the base of the tube
for adding such a bolt.

There is only so much clearance between the base and the tube,
though, so be sure any weight you add will not hinder the move­ment of the telescope.

A convenient “beanbag”-type counterweight system, designed
exclusively for Dobsonian telescopes, is also available from Orion
Telescopes & Binoculars.

Tracking Objects With the Telescope

You will notice that the telescope moves on two axes: azimuth and
altitude. The azimuth axis permits left-right motion (parallel to the
horizon) via the rotation of the Dobsonian baseplate. The altitude
axis allows up-down movement (perpendicular to the horizon)
through the pivoting of the two altitude bearings in the cradle.

When viewing near the zenith (straight overhead), the scope can
seem a little harder to move, especially in the azimuthal direction,
since there’s less leverage when the scope is pointed steeply
upward. In this case, it may be easier to rotate the base of the
scope with one hand, and raise or lower the tube with the other.

The focuser is a very handy point at which to move the telescope
with your hand. Applying hand pressure here tends to equalize the
force on each axis, and keeps your hands away from the front of
the tube. Don’t move the telescope around by the finder scope
because you might knock it out of alignment.

One of the nice things about your telescope is how easy it is to
follow the slow movement of a celestial object across the sky. You
never have to release a brake or clamp to the scope, or tighten
one once you are on the object. You simply give the telescope
tube a gentle nudge or tug with one hand and it will glide on its
bearings until you stop applying the pressure.

Celestial objects appear to move because of the rotation of the
Earth on its axis. When you observe an object through the eye­piece, you’ll see it slowly drift across the field of view. When it gets
near the edge of the field, give the tube a slight tug or push to
recenter the object. Objects will appear to move faster at higher
magnifications, when the field of view is narrower.

Astrophotography

Premium Deep Space Explorers are not suited for astrophotogra­phy. A 35mm camera will not come to focus when mounted on the
telescope.

5. Collimation of the Optics
(Aligning the Mirrors)

Focusing the Telescope

Your Premium Deep Space Explorer came with the type of
focuser you selected when you placed the order.

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 (on a rack-and-pinion or Crayford focuser) or rotate the
focuser drawtube (on a helical focuser) 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, 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 focuser
counterclockwise. You should soon see the point at which focus is
reached.

6

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 correctly 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.

Figure 4B. Secondary mirror
centered under focuser
tube, viewed through the
collimating Eyepiece (as are
the next two illustrations).

Figure 4A. The view down the focuser tube of a Newtonian
reflector with eyepiece removed. In this example, the optical
system is badly out of collimation.

Use a Collimation Tool

To aid in centering your line of sight down the focuser drawtube,
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 roughly 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 socket-head screws on the ends of the spider
vanes; the screw heads are located on the outside of the optical
tube (refer to Figure 3). You will need the small Allen wrench
(provided) for this. Unthread one bolt a small increment while
threading 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 roughly 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

Figure 4C. Secondary
mirror correctly aligned
(tilted).

Figure 4D. Primary mirror
correctly aligned. The
telescope’s optical system
is now collimated.

primary is obviously not centered, it will need to be repositioned
in its mirror cell.

Centering the Secondary Mirror Under the
Focuser

Next, if there is an eyepiece in the telescope, remove it. Look down
into the open focuser drawtube at the secondary (diagonal) mirror.
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 4A 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 drawtube,
it must be adjusted. It 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 secondary 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 threaded 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 (see Figure 3). 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 4B), make sure the two
nuts are threaded against the spider center support to hold the rod
securely in place.

7

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 4C). If
there isn’t, you’ll need to adjust the tilt of the secondary mirror. (It
helps to adjust the secondary mirror 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 socket-head alignment screws in the sec­ondary mirror holder enough to be able to rotate the holder with
your hand. Now look into the focuser and rotate the holder
slightly one way, then the other, until the reflection of the primary
mirror is as centered in the secondary mirror as it will get. It still
may not be perfectly centered yet, but that’s OK. Now secure the
holder in that rotational position by threading the four alignment
screws back in.

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 alignment 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 4C. Don’t worry that the reflection of the
secondary mirror (the smallest circle, with the reflection of your
eye in it) and spider are off-center (as also is the case in Figure
4C); you’ll 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 4C, 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 wing nuts at the
bottom of the optical tube, behind the primary mirror. Turn one
wing nut 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 reflection. You’ll
soon get a feel for which wing nuts to turn in which direction and
how far, until finally the secondary mirror reflection is dead center.
(It helps to have two people for primary mirror collimation, one to
look in the focuser while the other adjusts the wing nuts.)

The collimation bolts are spring-loaded, so once you achieve the
correct mirror tilt, just leave the wing nuts as they are; the mirror
will remain in the adjusted position.

The view through the Collimating Eyepiece should now resemble
Figure 4D. 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 and
Techniques

Pick a location away from streetlights 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 turbulence
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 overhead, 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 transpar­ency—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 equilibrium” 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 Premium DSE, allow at least 1 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.

Let Your Eyes Dark-Adapt

Don’t expect to go from a lighted house into the darkness of the
outdoors at night and immediately see faint nebulas, galaxies,
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

8

after several hours of total darkness. As your eyes become dark­adapted, 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 lights, streetlights and automobile headlights will ruin your
night vision.

Eyepiece Selection

Always start viewing with your lowest-power, widest-field eye­piece. After you’ve 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 magnfication 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’re using an Orion 10" Premium DSE, which
has a focal length of 1422mm, and a 26mm eyepiece, the power
would be

1422 ÷ 26 = 55x.

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 counterweight
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 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 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’s pretty time-consuming
and frustrating to hunt for objects randomly, without knowing
where to look. You should have specific targets 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, globular 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’ll 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 starlike. 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 generally
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 seeing) 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 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 “Double­Double” in the constellation Lyra and the gorgeous two-color

9

double star Albireo in Cygnus are favorites. Defocusing a star
slightly can help bring out its color.

if stored outside for long periods, exposed to the elements,
Sonotube can warp and begin to unravel.

Deep-Sky Objects

Premium Deep Space Explorers are short-focal-length, “fast”
Newtonians that are ideally suited for wide-field viewing of deep-sky
objects. Under dark skies, you can observe a wealth of such
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. Don’t 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 experienced 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 information
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. Care and Maintenance

Care of the Tube and Base

Give your telescope reasonable care and it will last a lifetime. Store
it indoors or in a dry garage or observatory; DO NOT leave it out­side where it is exposed to rain, humidity, or direct sunlight. 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 preserve 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 surfaces. 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. However,

Transporting your Premium Deep Space Explorer

When transporting your telescope, separate the base from the
tube and put the tube on a soft surface (back seat, blanket, etc.)
to keep it from getting banged around.

When shipping your telescope, should you have to, you must
protect the first-surface primary mirror.

1. Remove the primary mirror cell and mirror from the telescope
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 mirror
MUST be covered with a soft, nonabrasive material. In order
of preference: original tissue wrap, lots of lens cleaning 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 insure adequate protection.

Care of the Optics

Any quality optical lens cleaning tissue and optical lens cleaning
fluid specifically designed for multi-coated optics can be used to
clean the exposed lenses of your eyepieces or finder 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. Don’t take eyepieces apart for cleaning!

Cleaning First-Surface Mirrors

Cleaning is seldom needed (perhaps once a year) and is best
done only when definitely needed. Covering your telescope will
prevent the mirrors from getting dirty. Small specks of dust or
flecks of paint have virtually no affect on performance, so don’t
clean your mirror too often; it’s too much trouble for little reason!
Improper cleaning can scratch mirror coatings.

The primary mirror and secondary mirror of your telescope are
front-surface aluminized and overcoated with hard silicon monox­ide, which prevents the aluminum from oxidizing. These coatings
normally last through many, many years of use before requiring
recoating (which is easily done).

10

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 dampened 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 accumulate. 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 smudges 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 multi­coated 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

10" Premium DSE

Mirror: Pyrex, hand figured

Mirror Coatings: Enhanced 94%-reflective aluminized; silicon
monoxide overcoat

Primary mirror focal length: 1422mm

Primary mirror diameter: 10 inches

Secondary mirror diameter: 2.14 inches

Focal ratio: f/5.6

Weight: 77 lbs. (base 33 lbs., tube assembly 44 lbs.)

Tube length: 61 inches

Tube diameter (o.d.): 13 inches

Power with 26mm eyepiece: 55x

12.5" Premium DSE

Mirror Glass: Pyrex, hand figured

Mirror Coatings: Enhanced 94%-reflective aluminized; silicon
monoxide overcoat

Primary mirror focal length: 1524mm

Primary mirror diameter: 12.5 inches

Secondary mirror diameter: 2.60 inches

Focal ratio: f/4.8

Weight: 98 lbs. (base 37 lbs., tube assembly 61 lbs.)

Tube length: 65 inches

Tube diameter (o.d.): 15 inches

Power with 26mm eyepiece: 59x

Premium Deep Space Explorers are made in the U.S.A.

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One-Year Limited Warranty

This Orion Premium Deep Space Explorer Reflector is warranted against defects in materials or
workmanship for a period of one year from the date of purchase. This warranty is for the benefit of
the original retail purchaser only. During this warranty period Orion Telescopes & Binoculars will
repair or replace, at Orion’s option, any warranted instrument that proves to be defective, provided
it is returned postage paid to: Orion Warranty Repair, 89 Hangar Way, Watsonville, CA 95076. If the
product is not registered, proof of purchase (such as a copy of the original invoice) is required.

This warranty does not apply if, in Orion’s judgment, the instrument has been abused, mishandled,
or modified, nor does it apply to normal wear and tear. This warranty gives you specific legal rights,
and you may also have other rights, which vary from state to state. For further warranty service
information, contact: Customer Service Department, Orion Telescopes & Binoculars, P. O. Box 1815,
Santa Cruz, CA 95061; [phone].

Orion Telescopes & Binoculars

Post Office Box 1815, Santa Cruz, CA 95061

Customer Support Help Line [phone] • Day or Evening