Orion SkyQuest IntelliScope XT10 User manual

IN 179 Rev. D 05/07
Providing Exceptional Consumer Optical Products Since 1975
Customer Support [phone]
E-mail: [email protected]
Corporate Offices [phone]
P.O. Box 1815, Santa Cruz, CA 95061
INSTRUCTION MANUAL
Orion®
SkyQuest™ XT10 Classic
#9708 Dobsonian Reflecting Telescope

2
Secondary mirror holder with
4-vane spider (not visible)
Navigation knob
Right side panel
Front brace
Handle
Top baseplate
Ground baseplate
Finder scope
Finder scope bracket
Eyepiece
Focus knob
Optical tube
Altitude side bearing
CorrecTension (XT)
Friction Optimization system
Eyepiece rack
Primary
mirror cell
Left side panel
Figure 1. The SkyQuest XT10
Foot (3)

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Welcome to an exciting new world of adventure! Your SkyQuest XT10 Dobsonian is a high-quality opti-
cal instrument designed to bring you dazzling views of the outer reaches of our universe. With special
new innovations, such as the CorrecTension (XT) Friction Optimization system, large format focuser,
and deluxe accessory package, this telescope represents a giant leap forward in the evolution of the
Dobsonian. Whether you are brand-new to amateur astronomy or a seasoned stargazer, the SkyQuest
XT10 Dobsonian will provide many evenings of enjoyment and fascination.
Table of Contents
1. Unpacking. . . . . . . . . . . . . . . . . . . . . . . . 3
2. Assembly . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Using Your Telescope . . . . . . . . . . . . . . . 7
4. Collimation (Aligning the Mirrors) . . . . . 10
5. Astronomical Observing . . . . . . . . . . . . 12
6. Care and maintenance . . . . . . . . . . . . . 15
7. Specifications . . . . . . . . . . . . . . . . . . . . 16
1. Unpacking
The telescope will arrive in two boxes, one containing the
optical tube assembly and accessories, the other containing
the unassembled Dobsonian base. Be careful unpacking the
boxes. We recommend keeping the original shipping contain-
ers. In the event that the telescope needs to be shipped to
another location, or returned to Orion for warranty repair, hav-
ing the proper shipping containers will help ensure that your
telescope will survive the journey intact.
Make sure all the parts in the Parts List are present. Be sure
to check boxes carefully, as some parts are small. If anything
appears to be missing or broken, immediately call Orion
Customer Support (800-676-1343) or email sales@telescope.
com for assistance.
Parts List
Box #1: Optical Tube Assembly and Accessories
Qty. Description
1 Optical tube assembly
1 Dust cover
1 25mm Sirius Plössl eyepiece
1 10mm Sirius Plössl eyepiece
1 9x50 right-angle correct-image finder scope
1 Finder scope bracket with O-ring
1 4-hole eyepiece rack
1 Collimation cap
2 Eyepiece rack mounting wood screws (length 3/4")
2 Spring coils
2 Pull loops
4 Nylon spacers (black)
2 1/4" washers (black)
2 Phillips-head screws (black, length 1-3/4")
2 Screws with round knobs attached
Box #2: Dobsonian Base
Qty Description
1 Left panel
1 Right panel
1 Front brace
1 Top baseplate
1 Ground baseplate
12 Base assembly screws (length 2")
1 Hex key (4mm)
3 Plastic feet
3 Feet attachment wood screws (length 1")
1 Self-adhesive rubber bumper
1 Large hex-head screw (length 3")
2 3/8" washers
1 3/8" lock nut
1 Nylon spacer (white)
1 T-nut
1 Handle
2 Socket head cap screws, 5/16" (black)
2 5/16" washers (black)
2 5/16" nuts (black)
1 Hex key (6mm)
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. Assembly
Now that you have unpacked the boxes and familiarized
yourself with all the parts in front of you, it’s time to begin
assembly. The optics of the telescope are already installed
in the tube, so most of the required assembly concerns the
Dobsonian base.
Assembly of the Dobsonian base
Refer to Figure 2 during base assembly. The base need
only be assembled once, unless you disassemble it for long-
term storage. The assembly process takes about 30 minutes
and requires a Phillips screwdriver, an adjustable crescent
wrench, and the provided hex keys. When tightening screws,
tighten them until firm, but be careful not to strip the holes
by over-tightening. If you use an electric screwdriver, do final
tightening with a standard screwdriver to avoid stripping.
1. Screw the plastic feet into the underside of the ground
baseplate (A) using the self-tapping wood screws provid-
ed, with a Phillips screwdriver. Insert the screws through
the feet and thread them into the predrilled starter holes.
2. Loosely attach the front brace (B) to the two side panels
(C) with six of the base assembly screws in the predrilled
holes. Use the 4mm hex key to tighten the screws. The
side panels should be oriented so the SkyQuest labels are
facing outward. The front brace should be oriented so the
index mark is facing inwards. Do not completely tighten
the screws yet.
3. Attach the two sides (C) with the front brace attached to
the top baseplate (D) with the remaining six base assem-
bly screws in the predrilled holes. Tighten all six screws.
4. Tighten the six side screws installed earlier.
5. Insert the white nylon bushing (E) into the hole in the cen-
ter of the top baseplate (D). Tap the nylon bushing in so it
goes all the way into the top baseplate. The nylon bushing
should be flush with the top surface of the top baseplate.
6. Insert the T-nut (K) into the center hole of the ground
baseplate (A) so the nut’s flanged top is on the same
side of the baseplate as the Teflon pads. Thread the large
hex-head screw (G) with a 3/8" washer (F) attached up
through the ground baseplate and through the T-nut until it
is tight. Now position the top baseplate (D) (with side pan-
els attached) over the ground baseplate and lower it so the
screw goes through the nylon spacer in the center hole of
the top baseplate. Now thread the remaining 3/8" washer
(H) and lock nut (I) onto the screw’s shaft. You might need
to hold the screw’s head in place with another crescent
wrench or pliers. Tighten the lock nut with a wrench just
enough to allow a slight separation of the top and bottom
baseplates when the mount is lifted. The purpose of the
lock nut is merely to keep the two baseplates from com-
ing apart when moving the telescope. Overtightening the
lock nut (I) will make the mount difficult to rotate in the
azimuthal (horizontal) direction.
7. Attach the handle (J) to the front brace (B) with the two
black socket-head cap screws. Insert the screws through
the handle and into the predrilled holes. Place the 5/16"
washers and 5/16" nuts on the protruding ends of the
screws. Tighten the nuts with a crescent wrench while
holding the screws stationary with the 6mm hex key.
8. The rubber bumper (L) provides a convenient “stop” for
the telescope’s altitude motion; it prevents the telescope
mirror cell from being knocked against the hard surface
of the base’s front brace. At the bottom of the interior sur-
face of the front brace, you will notice a small index mark
engraved. Remove the backing from the rubber bumper
and position the bumper over the index mark, as shown in
Figure 3. Press firmly so the adhesive holds the bumper
securely in place.
Figure 2. Exploded view of the Dobsonian base.
C
C
B
D
J
A
F
I
H
K
L
E
G
Figure 3. Position the rubber bumper “stop” over the index mark
on the inside surface of the front brace.

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Installing the Eyepiece Rack
The aluminum eyepiece rack is a standard accessory on
SkyQuest XT10 Dobsonians. It holds three 1.25" eyepieces and
one 2" eyepiece in a convenient place on the base, within easy
reach while you’re observing. A 1.25" barlow lens also can be
held in the rack. About halfway down the left side panel of the
base you will notice two predrilled starter holes, about 6" apart.
Take the black wood screws and thread them into the starter
holes with a Phillips screwdriver. Then you can “keyhole” the
eyepiece rack onto the wood screws and continue tightening
the screws (Figure 4). If you want to be able to remove the rack,
do not tighten the screws too tightly. Be certain that the screws
are loose enough that you can lift the rack and remove it from
the screws through the larger part of the keyhole. If you want to
have the rack permanently attached, thread the screws tightly.
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 (Figure 5). The unique
flange design of the altitude bearing allows for automatic left-
to-right centering of the optical tube in the cradle. Once in the
cradle, the tube should pivot freely up and down with gentle
hand pressure. Note that the tube will not yet be properly bal-
anced, since the eyepiece and finder scope are not in place,
and the CorrecTension system has not been installed.
Installing the CorrecTension (XT) Friction
Optimization System
Perhaps the most exciting new feature of the SkyQuest XT10
Dobsonian is the CorrecTension Friction Optimization sys-
tem. Because of their relatively light weight, 10" and smaller
Dobsonians have always been plagued by insufficient friction
on the altitude bearing surfaces. As a result, such telescopes
move up and down much too freely. This causes problems
when the observer tries to accurately center and track an
object for viewing, especially at higher powers. Also, the tele-
scope becomes very sensitive to balance, requiring additional
equipment such as counterweight systems or adjustable side
bearings to compensate.
SkyQuest XT10 Dobsonians employ a simple yet effective
remedy for the friction problem that obviates the need for
such cumbersome countermeasures. CorrecTension Friction
Optimization utilizes a spring coil to “pull” the tube assem-
bly down onto the altitude bearing pads, thereby increasing
the friction by just the right amount. With CorrecTension, you
can change eyepieces or add a barlow lens without having to
tediously adjust the telescope’s balance as you would with other
Dobsonians. The altitude friction will roughly equal the azimuth
friction, ensuring optimal performance.
To install the CorrecTension assembly, follow these steps while
referring to Figure 6:
1. Put one of the black nylon spacers on a black Phillips head
screw. The spacer should be oriented so the narrow end
seats against the head of the screw. Slip one of the black
1/4" washers over the end of the screw. Now, thread the
screw into the hole in the base side panel just below the cra-
dle. The screw will thread into the preinstalled insert in the
hole. Use a Phillips screwdriver to tighten the screw. Repeat
this procedure on the opposite side panel.
Figure 4. Using the two supplied screws, install the aluminum
eyepiece rack in the predrilled holes about halfway down the left side
panel of the base.
Figure 6. Close-up view of the CorrecTension system.
Black nylon
spacers
1/4" washer
(black)
Altitude side bearing
Screw w/round knob
Spring
Phillips head
screw (black)
Pull loop
Figure 5. Set the optical
tube on the “cradle” of the
base so that the altitude side
bearings on the tube rest on
the white plastic “pads.”

2. Next, insert one of the screws with round plastic knob
attached through the end ring of one of the springs. Slip
a black nylon spacer onto the screw. Orient the spacer so
the narrow end is closest to the knob. Thread the entire
assembly into the hole in the center of the telescope’s alti-
tude side bearing until tight. The end ring of the spring
should seat onto the narrow end of the spacer. Repeat this
procedure for the other altitude side bearing.
3. Attach a pull loop to the free end of each spring. Slide
the loop through the opening in the ring on the end of the
spring.
4. Now, pull each spring down using the pull loop, and posi-
tion the spring’s end ring over the head of the Phillips
screw (installed in step 1) and onto the narrow part of the
nylon spacer, as shown in Figure 7. You needn’t attach
both springs simultaneously; one at a time is fine.
The CorrecTension system is now installed and engaged.
If you wish to remove the telescope from the base, you will
first need to disconnect the springs from the “posts” on the
Dobsonian base. The springs will remain captive on the alti-
tude side bearings, so they will not get lost.
Installing the Finder Scope
The SkyQuest XT10 comes with a high-quality 9x50 right-
angle correct-image achromatic finder scope (Figure 8a) as
standard equipment. A finder scope greatly aids in finding
objects to view in the night sky, which will be discussed in
detail later. The “9” denotes the finder scope’s 9 power magni-
fication while the “50” means it has a 50mm diameter lens.
The finder scope arrives pre-installed in its bracket, but must
be placed into the dovetail holder on the telescope tube. Slide
the base of the finder scope into the dovetail holder located
adjacent to the focuser (Figure 8b). Lock the bracket into posi-
tion by tightening the knurled thumbscrew on the dovetail
holder.
Inserting an Eyepiece
The final step in the assembly process is to insert an eye-
piece into the telescope’s focuser. Take the cover cap off the
end of the focuser drawtube. Loosen the thumb screw on the
1.25" eyepiece adapter (see Figure 9). Do not loosen the two
thumb screws on the 2" eyepiece adapter. Insert one of the
supplied eyepieces, then secure it by retightening the thumb
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Figure 7. (a) To attach the spring to the base, grip the pull loop
with your index finger and pull down on the spring. (b) While pulling
down, slip the end ring of the spring over the screw head and onto the
narrow part of the nylon spacer, then release the pull loop.
a.
b.
Figure 8a. The 9x50 right-angle correct-image finder scope.
Tensioner
Correct-image
prism housing
Finder scope bracket
Focus lock ring Alignment thumbscrews
Figure 8b. Inserting the finder scope into its dovetail holder.
Dovetail holder
Knurled thumbscrew
Finder scope bracket

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screw on the 1.25" eyepiece adapter. The other eyepiece can
be placed in the eyepiece rack until it is needed.
The assembly of your SkyQuest Dobsonian is now complete.
It should appear as shown in Figure 1. The dust cover on the
front of the telescope tube should always remain in place
when the telescope is not in use. It is also a good idea to store
eyepieces in an eyepiece case and to replace the cover caps
on the focuser and finder scope when the telescope is idle.
3. Using Your Telescope
It is best to get a feel for the basic functions of the SkyQuest
XT10 Dobsonian during the day, before observing astro-
nomical objects at night. This way you will not have to fumble
around trying to orient yourself in the dark! Find a spot out-
doors where you have plenty of room to move around the
telescope, and where you have a clear view of some object
or vista that is at least 1/4-mile away. It is not critical that the
base be exactly level, but it should be placed on somewhat
flat ground or pavement to ensure smooth movement of the
telescope.
Remember, never point the telescope at or near the Sun with-
out using a proper solar filter over the front aperture!
Altitude and Azimuth
The Dobsonian base of the SkyQuest XT10 permits motion
of the telescope along two axes: altitude (up/down) and azi-
muth (left/right) (see Figure 10). This is very convenient, since
up/down and left/right are the most “natural” ways that people
aim. As a result, pointing the telescope is exceptionally easy.
Simply take hold of the navigation knob and move it left or
right so the base rotates about its central azimuth bolt, and
move it up or down so the altitude side bearings rotate in the
base’s cradle. Both motions can be made simultaneously and
in a continuous manner for easy aiming. Move the telescope
gently - let it glide. In this way you can point the telescope to
any position in the night sky, from horizon to horizon.
Focusing the Telescope
With the 25mm eyepiece inserted in the focuser, move the
telescope so the front (open) end is pointing in the general
direction of an object at least 1/4-mile away. 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’ve hit the exact focus point.
If you have trouble focusing, rotate the focusing knob so the
drawtube is in as far as it will go. Now look through the eye-
piece while slowly rotating the focusing knob in the opposite
direction. You should soon see the point at which focus is
reached.
The thumb screw located on the bottom of the focuser body
(Figure 9) will lock the focuser drawtube in place once the
telescope is properly focused. Before focusing, remember
to first loosen the focus lock thumb screw. Do not loosen the
thumb screw too much as there must be some tension to
keep the drawtube secure within the focuser.
If you find the drawtube tension when focusing is either too
tight (focus knob is difficult to turn) or too loose (image shifts
when focusing or drawtube moves inward by itself), the ten-
sion can be adjusted for optimal performance. The focusing
tension adjustment set screw is a 3mm socket head set
screw located below the focus lock thumb screw (Figure 9).
A 3mm hex key is required for adjustment of focus tension.
Viewing with Eyeglasses
If you wear eyeglasses, you may be able to keep them on
while you observe. This requires your eyepieces to have
enough eye relief to allow you to see the whole field of view.
You can see if your eyepieces have enough eyerelief by look-
ing through the eyepiece first with your glasses on and then
with them off, and see if the glasses restrict the view to only a
Figure 9. The 2" Crayford focuser with eyepiece adapters
attached. the focuser will accept eyepieces with barrel diameters of
1.25" and 2".
Altitude
Figure 10. The SkyQuest has two axes of motion: altitude (up/
down) and azimuth (left/right).
Azimuth
2" eyepiece adapter
1.25" eyepiece
adapter
Focus lock
thumbscrew
Tension adjustment screw

8
portion of the full field. If they do, you can easily observe with
your glasses off by just refocusing the telescope the needed
amount. If you suffer from severe astigmatism, however, you
may find images noticeably sharper with your glasses on.
Aligning the Finder Scope
The finder scope must be aligned accurately with the tele-
scope for proper use. To align it, first aim the main telescope
in the general direction of an object at least 1/4-mile away
- the top of a telephone pole, a chimney, etc. Position that
object in the center of the telescope’s eyepiece.
Now look in the finder scope. Is the object visible? Ideally it
will be somewhere in the field of view. If not, some coarse
adjustment to the finder scope bracket’s alignment thumb-
screws will be needed until the object comes into the finder
scope’s field of view.
The SkyQuest XT10’s finder scope uses a spring-loaded
bracket that makes alignment of the finderscope very easy. As
you turn either of the thumbscrews, the spring in the bracket’s
tensioner moves in and out to keep the finder scope secure
in the bracket.
Note: The image the main telescope will appear upside-
down (rotated 180°). This is normal for reflector telescopes
(see Figure 11).
With the image in the finder scope’s field of view, you now
need to fine-adjust the alignment thumbscrews to center the
object on the intersection of the crosshairs. Adjust the aim of
the finder scope by turning the thumbscrews, one at a time,
until the object is centered.
The finder scope alignment needs to be checked before
every observing session. This can easily be done at night,
before viewing through the telescope. Choose any bright star
or planet, center the object in telescope eyepiece, and then
adjust the finder scope bracket’s alignment thumbscrews until
the star or planet is centered on the finder’s crosshairs.
Focusing the Finder Scope
If, when looking through the finder scope, the images appear
somewhat out of focus, you will need to refocus the finder
scope for your eyes. Loosen the lock ring located behind the
objective lens cell on the body of the finder scope (see Figure
8a). Back the lock ring off by a few turns, for now. Refocus the
finder scope on a distant object by threading the objective
lens cell in or out on the finder scope body. Precise focusing
will be achieved by focusing the finder scope on a bright star.
Once the image appears sharp, retighten the lock ring behind
the objective lens cell. The finder scope’s focus should not
need to be adjusted again.
Aiming/Pointing the Telescope
With the finder scope aligned, the telescope can be quick-
ly and accurately pointed at anything you wish to observe.
The finder scope has a much wider field of view than the
telescope’s eyepiece, and therefore it is much easier to first
center an object in the finder scope. Then, if the finder scope
is accurately aligned, the object will also be centered in the
telescope’s field of view.
Start by once again moving the telescope until it is pointed
in the general direction of the object you want to see. Some
observers find it convenient to sight along the tube to do this.
Now, look in the finder scope. If your general aim is accu-
rate, the object should appear somewhere in the field of view.
Make small adjustments to the telescope’s position until the
object is centered on the finder’s crosshairs. Now, look in the
telescope’s eyepiece and enjoy the view!
Magnification
Once the object you want to view is well centered in the 25mm
eyepiece, you may want to increase the magnification to get
a closer view. Loosen the thumbscrew on the 1.25" eyepiece
adapter and remove the eyepiece. Place it in the eyepiece
rack, if you wish. Insert the 10mm eyepiece into the 1.25"
eyepiece adapter, then retighten the thumbscrew. If you were
careful not to bump the telescope, the object should still be
centered within the field of view. Notice that the object being
viewed is now larger, but somewhat dimmer.
The SkyQuest XT10 is designed to accept any eyepiece with
a barrel diameter of 1.25" or 2". Magnification, or power, is
determined by the focal length of the telescope and the focal
length of the eyepiece. Therefore, by using eyepieces of differ-
ent focal lengths, the resultant magnification can be varied.
Magnification is calculated as follows:
Telescope Focal Length (mm)
Magnification= Eyepiece Focal Length (mm)
The SkyQuest XT10 Dobsonian has a focal length of 1200mm.
So, the magnification with the supplied 25mm eyepiece is
1200mm = 48x
25mm
The magnification provided by the 10mm eyepiece is
1200mm = 120x
10mm
The maximum attainable magnification for a telescope is
directly related to how much light its optics can collect. A tele-
scope with more light collecting area, or aperture, can yield
Naked-eye view
Figure 11. The view through a reflector telescope is upside
down.
View through telescope

9
higher magnifications than a smaller aperture telescope. The
maximum practical magnification for any telescope, regard-
less of optical design, is about 60x per inch of aperture. This
translates to about 600x for the SkyQuest XT10.
Keep in mind that as magnification is increased, the bright-
ness of the object being viewed will decrease; this is an
inherent principle of the physics of optics and cannot be
avoided. If magnification is doubled, an image appears four
times dimmer. If magnification is tripled, image brightness is
reduced by a factor of nine!
Note About High Magnifications:
Maximum magnifications are achieved only under the most
ideal viewing conditions at the best observing sites. Most of
the time, magnifications are limited to 200x or less, regard-
less of aperture. This is because the Earth’s atmosphere
distorts light as it passes through. On nights of good “seeing”,
the atmosphere will be still and will yield the least amount of
distortion. On nights of poor seeing, the atmosphere will be
turbulent, which means different densities of air are rapidly
mixing. This causes significant distortion of the incoming light,
which prevents sharp views at high magnifications.
Tube Balance
Dobsonians are designed to balance with standard supplied
accessories, such as an eyepiece and a finder scope. But
what if you want to use other accessories such as a barlow
lens or a heavy 2" eyepiece? Traditional Dobsonian designs
expect the user to compensate for heavier accessories by
adding weight to the opposite end of the telescope tube. Such
counterweighting systems can be expensive and unwieldy.
The CorrecTension Friction Optimization system of the
SkyQuest XT10 Dobsonian, however, solves the finicky bal-
ance problem. The spring coils pull the tube down onto the
base, thereby increasing the friction on the altitude bearing
pads. With CorrecTension, the added weight of small front-end
loads will not adversely affect the balance of the telescope.
If you install an array of heavier accessories onto your
SkyQuest XT10’s optical tube, you may need at some point to
counterbalance the telescope with a counterweight system.
Carrying the Telescope
Moving the SkyQuest XT10 is easy to do. Remove any eye-
pieces from the telescope and eyepiece rack, and place
them in an eyepiece case. You can also remove the finder
scope and finder scope bracket, if you wish. Disengage the
CorrecTension springs by unhooking them from the posts on
the base, using the pull loops. The springs remain captive on
the telescope side bearings. The base and tube are now dis-
engaged and can be transported separately.
To carry the base, simply grasp the handle on the front of it.
The tube should be carried with two hands. One way to do
this is to grasp the tube with one hand while grasping the mir-
ror cell end with the other (Figure 12). Another way is to grasp
the tube with both hands around its circumference (Figure
13). Be careful when setting the tube down on its end so as
not to bend or damage the primary mirror collimation screws
on the bottom of the primary mirror cell.
When putting the SkyQuest into a vehicle, common sense
prevails. It is especially important that the optical tube does
not knock around; this can cause the optics to become mis-
aligned, and could dent the tube. We recommend transporting
and storing the tube assembly in a padded case for proper
protection.
Figure 12. You
can carry the tube
by grasping the
tube with one hand
while grasping the
mirror cell end with
the other.
Figure 13. Another way to carry
the tube is to grasp the tube with both
hands around its circumference.

10
4. Collimation
(Aligning The Mirrors)
Collimation is the process of adjusting the mirrors so they
are properly aligned with one another. Your telescope’s optics
were aligned at the factory, and should not need much adjust-
ment unless the telescope is handled roughly. Accurate mirror
alignment is important to ensure the peak performance of
your telescope, so it should be checked regularly. Collimation
is relatively easy to do and can be done in daylight.
To check collimation, remove the eyepiece and look down the
focuser drawtube. You should see the secondary mirror cen-
tered in the drawtube, as well as the reflection of the primary
mirror centered in the secondary mirror, and the reflection of
the secondary mirror (and your eye) centered in the reflection
of the primary mirror, as in Figure 14a. If anything is off-cen-
ter, as in Figure 14b, proceed with the following collimation
procedure.
The Collimation Cap and Mirror Center Mark
Your SkyQuest XT10 comes with a collimation cap. This is
a simple cap that fits on the focuser drawtube like a dust
cap, but has a hole in the center and a silver bottom. This
helps center your eye so that collimation is easy to perform.
Figures 14b through 14e assume you have the collimation
cap in place.
In addition to the collimation cap, the primary mirror is marked
with a circle at its exact center. This “center mark” allows you
to achieve a precise collimation of the primary mirror; you
don’t have to guess where the center of the mirror is. You
simply adjust the mirror position (described below) until the
reflection of the hole in the collimation cap is centered in the
ring. The center mark is also required for best results when
using other collimating devices, such as Orion’s LaserMate
Laser Collimator, obviating the need to remove the primary
mirror and mark it yourself.
Note: The center ring sticker need not ever be removed
from the primary mirror. Because it lies directly in the
shadow of the secondary mirror, its presence in no way
adversely affects the optical performance of the telescope
or the image quality. That might seem counterintuitive,
but its true!
Aligning the Secondary Mirror
With the collimation cap in place, look through the hole in the
cap at the secondary (diagonal) mirror. Ignore the reflections
for the time being. The secondary mirror itself should be cen-
tered in the focuser drawtube, in the direction parallel to the
length of the telescope. If it isn’t, as in Figure 14b, it must be
adjusted. This adjustment will rarely, if ever need to be done. It
helps to adjust the secondary mirror in a brightly lit room with
the telescope pointed towards a bright surface, such as white
paper or wall. Also placing a piece of white paper in the tele-
scope tube opposite the focuser (in other words, on the other
side of the secondary mirror) will also be helpful in collimating
the secondary mirror. Using a 2mm hex key, loosen the three
small alignment set screws in the center hub of the 4-vaned
spider several turns. Now hold the mirror holder stationary (be
careful not to touch the surface of the mirrors), while turning
the center screw with a Phillips head screwdriver (See Figure
15). Turning the screw clockwise will move the secondary mir-
Figure 14. Collimating the optics. (a) When the mirrors are
properly aligned, the view down the focuser drawtube should
look like this (b) With the collimation cap in place, if the optics
are out of alignment, the view might look something like this. (c)
Here, the secondary mirror is centered under the focuser, but it
needs to be adjusted (tilted) so that the entire primary mirror is
visible. (d) The secondary mirror is correctly aligned, but the primary mirror still needs adjustment. When
the primary mirror is correctly aligned, the “dot” will be centered, as in (e).
a.
b. c.
d. e.