Orion SkyQuest 10135XT12g User manual

INSTRUCTION MANUAL
IN 388 Rev. C 06/12
Customer Support [phone] • E-mail: [email protected]
Corporate Offices [phone] • 89 Hangar Way, Watsonville, CA 95076
© 2010-2012 Orion Telescopes & Binoculars
Orion® SkyQuest™ XTg
GoTo Dobsonians
#10134 XT8g, #10135 XT10g, #10136 XT12g
Providing Exceptional Consumer Optical Products Since 1975
OrionTelescopes.com

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Figure 1. Overview of SkyQuest XTg Dobsonian (12" shown)
Navigation knob
Altitude motor
housing
12.5mm Illuminated
Plössl 1.25" eyepiece
Eyepiece rack
Dobsonian base
Polyethylene foam
dust guard
EZ Finder II
28mm DeepView
2" eyepiece
2" Dual-speed
Crayford focuser
Optical tube
Handle
Handle
Tube
connecting knob
GoTo hand
controller
Azimuth
motor housing
(not shown)

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Congratulations on your purchase of an Orion
SkyQuest XTg GoTo Dobsonian. It is an observer’s
dream telescope, offering quality diffraction-limited
optics; a stylish, easy-to-setup base outfitted with
automated, computerized GoTo technology; and a
sturdy design. This high-performance astronomical
instrument will provide dazzling views of celestial
objects, yet be transportable and wonderfully easy
to use.
With the alt-azimuth GoTo system, you simply select an object
from the 42,900 object database and the telescope will take
you there with the push of a couple of buttons. Searching for
objects is a thing of the past, as the GoTo servo motors and
computerized database find them for you in seconds, then
track them while you enjoy the view! Deluxe features such as
a 2" dual-speed Crayford focuser, enhanced-reflectivity mirror
coatings, and full accessory assortment provide everything
you need to enjoy your journey through the universe.
Please read these instructions thoroughly before beginning
assembly and subsequent use of the telescope.
1. Unpacking
The telescope is packed in two boxes, one containing the opti-
cal tube assembly and accessories, another containing the
unassembled Dobsonian base. The 12" model has a third box
containing the primary mirror in its cell. Be careful unpacking
the boxes. We recommend keeping the original packaging. In
the event that the telescope needs to be shipped to another
location, or returned to Orion for warranty repair, having the
proper packaging will help ensure that your telescope will sur-
vive the journey intact.
Before beginning assembly, unpack each box and confirm
that all of the parts in the Parts List below are present. The
parts are listed by the box they should arrive in, but some
of the parts may be in different boxes than indicated below.
Be sure to check all boxes carefully, as some parts are
small. If anything appears to be missing or broken, immedi-
ately call Orion Customer Support (800-676-1343) or email
suppor[email protected] for assistance.
Parts List
Box #1: Optical Tube Assembly and Accessories
(Refer to Figure 2)
Qty. Description
1 Optical Tube Assembly
1 Dust cover
1 28mm Deep View eyepiece, 2" barrel diameter
1 12.5mm Illuminated Plössl eyepiece, 1.25" barrel
diameter
1 EZ Finder (with bracket)
1 Collimation cap
1 Eyepiece rack
2 Eyepiece rack wood screws (20mm long, color black)
2 Hex keys (2mm, 3mm)
1 Tube connecting knob
1 Hand controller holster (with 2 assembly screws)
A
B
C
D
E
F
G
H
I
J
Figure 2. Contents of the optical tube box: A) Optical tube,
B) Dust cap, C) Holster with mounting screws, D) EZ Finder II
with bracket, E) Hex keys, F) collimation cap, G) 1.25" 12.5mm
illuminated Plössl eyepeice, H) 2" 28mm DeepView eyepiece, I)
Starry Night CD-ROM, J) eyepiece rack with mounting screws.
Table of Contents
1. Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. The GoTo Hand Controller . . . . . . . . . . . . . . . . . . . . . . 10
4. Setup for AutoTracking or GoTo Mode . . . . . . . . . . . . . 11
5. Using the Telescope in AutoTracking Mode . . . . . . . . . 12
6. Alignment for GoTo Operation . . . . . . . . . . . . . . . . . . . 12
7. Using the Telescope in GoTo Mode . . . . . . . . . . . . . . . 14
8. Collimating the Optical System . . . . . . . . . . . . . . . . . . 20
9. Using Your Telescope . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10. Astronomical Observing. . . . . . . . . . . . . . . . . . . . . . . . 23
11. Care and Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . 25
12. Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Menu Tree. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Appendix A: Time Zones of the World . . . . . . . . . . . . . . . . 29
Appendix B: RS-232 Connection . . . . . . . . . . . . . . . . . . . . 30
Star Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

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Box #2: Dobsonian Base
(Refer to Figures 3 and 4)
Qty. Description
1 Left side panel (with altitude motor pre-installed)
1 Right side panel
1 Front panel
2 Side braces (XT12g only, not shown)
1 Baseplate assembly (with azimuth motor pre-installed)
6 Base assembly wood screws (coarse thread, 47mm
long) (Quantity 12 for XT12g)
8 Base assembly machine screws (fine thread, 60mm
long) (Quantity 10 or XT12g)
8 Washers for base assembly machine screws (Quantity
10 or XT12g)
3 Handles
6 Handle mounting screws (hex head, 25mm long)
3 Hex keys (size 2mm, 4mm, 6mm)
3 Plastic feet
3 Feet wood screws (1" long)
1 Hand controller
1 Hand controller cable (coiled)
1 Azimuth motor connection cable
1 RS-232 computer cable
Box #3: Primary Mirror and Cell (12" model only)
Qty. Description
1 Primary mirror
1 Mirror cell
3 Collimation knobs
3 Nylon washers (3/4" outer diameter)
3 Springs
Figure 3. SkyQuest XTg base components. The XT12g base also
includes two side braces, not shown.
Figure 5. Polyethylene foam dust guard between ground
baseplates. DO NOT REMOVE!
Figure 6. Starter holes for feet.
Figure 4. Base hardware for SkyQuest XTg.
Left
panel
(with
altitude
motor)
Ground baseplate assembly
(with azimuth motor)
Front panel
Right
panel
Cables
Hand controller
Base hardware
and handle
Screwdriver
Hex keys
Machine
screws
with
washers
Base
assembly
wood
screws
Tube connecting
knob
Base feet
Wood
screws
WARNING: Never look directly at the Sun through your tele-
scope 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 is time to begin
assembly.
Assembly of the Dobsonian Base
The base need only be assembled once, unless you disas-
semble it for long-term storage. The assembly process should
take about half an hour. All necessary tools are included in
the packages. The two ground baseplates arrive preassem-
bled with the motors, optical encoders, and motor housings
installed. There is a protective strip of polyethylene foam
material between the two base plates (Figure 5). Do not
attempt to remove this material; it is glued in place. It is
designed to keep dust out of the azimuth motor assembly
and gears.
During initial assembly it is suggested to fasten the screws
just enough to hold the panels together loosely. When all of
the components are assembled, then perform the final tight-
ening of each screw one or two turns at a time, alternating
from one screw to the next to ensure all are tightened evenly.
When tightening screws, tighten them until firm, but be careful
not to strip the holes by over-tightening.
1. Turn the baseplate assembly upside-down and gently
rest it on the azimuth motor housing. Locate the three
starter holes on the perimeter of the bottom baseplate
(Figure 6). Insert the screws through the feet and thread
them into the predrilled starter holes (Figure 7) with the
supplied Phillips screwdriver until tight.
2. Connect the side panels to the front panel (Figure 8).
Use the coarse thread socket-head screws for this. There
are unthreaded pilot holes (without the metal collar) to
align these pieces. Orient the side panels so the oval
XTg label is facing outward. Orient the front panel so that
the pilot holes for the handle and eyepiece rack face out.
The side panel with the motor attached is the left panel.
There are six screws total (three for each side) to assem-
ble. Start by inserting the screws and turning by hand
to ensure they are going in straight. When you begin to
meet resistance use the 4mm hex key to complete this
step. Do not completely tighten the screws yet. Having
the boards a little loose will help in aligning the assembly
to the top baseplate in step 3. The completed assembly
should look like Figure 9.
2a. [For XT12g only] Attach a side brace to the outside sur-
face of both the left and right side panels. Each side brace
is attached with three base assembly wood screws. Insert
the screws through the corresponding pre-drilled holes in
the side panel and then thread them into the brace using
the included 4mm hex key.
Figure 7. Attaching the base feet to the base. Figure 8. Secure the front panel to each side panel.
Figure 9. The completed side panel and front panel assembly
(XT10g shown).

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3. Carefully position the assembled structure onto the top
baseplate by aligning the holes in the cutouts of the front
and side panels to the corresponding threaded metal col-
lar inserts on the top baseplate (Figure 10). Insert the
base assembly machine screws and tighten (Figure 11).
Once this setup is complete you may firmly tighten the
six base assembly screws installed in the previous step.
4. Attach the handles to the base. There are three handles,
one for each side panel and one for the front panel. Use
the 6mm hex key and the large socket head cap screws
to install the handles. Each handle is the same so it does
not matter which handle is used for any particular panel.
Refer to Figure 1 for handle placement.
5. The aluminum eyepiece rack holds three 1.25" eyepieces
and one 2" eyepiece in a convenient place on the base,
within easy reach while you are observing. The eyepiece
rack and its mounting screws can be found in the box
with the optical tube. Attach the eyepiece rack on the
front panel above the handle. There are two small pilot
holes on the front panel approximately 6" apart. Thread
the small Phillips-head screws into the holes but do
not tighten completely yet. Place the eyepiece rack on
those screws using the wide holes on the rack and slide
it downward so the narrow portion is under the screws.
Now tighten the screws to secure the rack in place.
6. The XTg series includes a convenient holster to place the
hand controller in when not in use. The holster installs on
the altitude motor. Locate the two small pilot holes and
attach the holster using the small screws until just tight.
Do not over-tighten these screws!
7. Now install the azimuth motor connection cable. It is a flat
cable that has an 8-pin RJ-45 plug on both ends. Plug
one end into the jack on the azimuth motor housing on
the top baseplate; plug the other end into the jack labeled
AZ MOTOR on the altitude motor housing (Figure 23).
8. Finally, connect the GoTo hand controller. Plug the wide
RJ-45 connector on the coiled hand controller cable into
the corresponding port on the hand controller. Plug the
smaller RJ-12 connector into the port labeled HC on the
altitude motor housing.
Assembly of the Optical Tube (XT12g Only)
Both the XT8g and XT10g optical tubes arrive completely
assembled from the factory. If you have one of these mod-
els, you may skip ahead to the next section, “Connecting the
Optical Tube to the Dobsonian Base”.
Due to its large size, and in order to prevent damage to the
primary mirror in shipment, the 12" mirror is shipped in its
cell separately from the optical tube. Once the primary mir-
ror is installed into the telescope, there will be no need to
remove the mirror except for occasional cleaning (see “Care
& Maintenance”).
1. To install the mirror cell into the optical tube, the rear end
ring attached to the lower section of the optical tube must
first be removed. This is done by unthreading and remov-
Figure 10. Align the holes on the side panels with the threaded
inserts in the baseplate.
Figure 11. Base assembly machine screws set in place, but not
yet tightened.
Figure 12. To remove the rear end ring, unthread the six screws
that connect it to the tube.
Threaded inserts
Cutout holes

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ing the six Phillips-head screws that connect the end ring
to the tube (Figure 12), and then pulling the end ring off
the tube.
Warning: Once the rear end ring is removed from the
tube, the raw edge of the tube itself will be exposed. Be
careful not to cut or otherwise hurt yourself on the tubeís
edge. Also, be careful not to pinch your fingers when re-
attaching the assembled mirror cell onto the tube.
2. Next, assemble the rear end ring to the mirror cell. Find a
clean, flat surface, and turn the mirror cell over so that the
mirror is facing downwards. Place the three springs onto
the three exposed threaded shafts (Figure 13). Lower
the end ring onto the mirror cell so the threaded shafts
pass through it, and the end ring rests on the springs
(Figure 14). Add a nylon washer to each collimation
knob and thread the collimation knobs through the end
ring and onto the threaded shafts (Figure 15). Make sure
the knobs have at least three full turns of engagement
on the shafts. The mirror cell is now ready to be installed
onto the lower tube section.
3. Assembling the end ring back onto the tube can be a bit
tricky. This is because the large diameter and thin alumi-
num of the tube will cause the tube to become somewhat
out of round once the end ring is removed. To assemble
the rear end ring (with mirror and mirror cell now con-
nected) to the tube, stand the tube up vertically so the
raw edge of the tube is facing upwards. Line up the
threaded holes in the edge of the mirror cell end ring with
the holes in the end of the tube. Then, lower the entire
mirror cell assembly onto the tube. There may be a bulge
in the perimeter of the tube which prevents the mirror
cell from fully seating onto the tube (Figure 16). Press
against this bulge, and the entire mirror cell should seat
onto the tube. Now, replace the six Phillips-head screws
that connect the rear end ring to the tube.
Figure 16. Locate the area of tube that is bulging out and
preventing the end ring from fully seating.
Figure 13. Place the three springs on the exposed threaded
shafts of the mirror cell.
Spring Shaft
Figure 14. Lower the rear end ring onto the mirror cell so that the
threaded shafts pass through the end ring, and the end ring rests on
the springs.
Figure 15. Thread the collimation knobs, with nylon washers
attached, through the rear end ring and onto the threaded shafts.
Make sure the knobs have at least three full turns of engagement on
the shafts.
Collimation
knob
Nylon
washer

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Connecting the Optical Tube to the
Dobsonian Base
The telescope is now assembled and ready to be placed into
the Dobsonian base. The left altitude hub on the optical tube
has a dovetail slot that slides into the altitude axis trunnion on
the inside of the left side panel (Figure 17). We recommend
orienting the trunnion such that the threaded hole for the tube
securing knob is facing upward. Then the telescope tube can
be cradled horizontally and just lowered into the base by gen-
tly sliding tube’s dovetail altitude hub into the mating recep-
tacle of the altitude trunnion on the base (Figure 18). (Get
help lifting the tube in place if it is too heavy or unwieldy for
you.) The tube should now be resting in a balanced, horizon-
tal position in the base. Then just insert and tighten the tube
connecting knob to secure the tube in place (Figure 19).
Accessory Installation
Now that the base is assembled and the optical tube installed
all that remains is to attach the EZ Finder II reflex sight and
the eyepiece. These accessories can be found in a small box
within the optical tube assembly box.
EZ Finder II
Using the included dovetail mounting bracket, the EZ Finder
II will slip neatly into the dovetail base preinstalled on your
SkyQuest optical tube. The EZ Finder II arrives pre-installed
in the mounting bracket. Just simply slide the dovetail mount-
ing bracket into the telescope’s dovetail mounting base and
tighten the thumbscrew on the base to secure the mounting
bracket.
Operating the EZ Finder II
The EZ Finder II works by projecting a tiny red dot (it is not a
laser beam) onto a lens mounted in the front of the unit. When
you look through the EZ Finder II, the red dot will appear to
float in space, helping you to pinpoint your target object. The
red dot is produced by a light-emitting diode (LED) near the
rear of the sight. A 3-volt lithium battery provides the power
for the diode. Turn the power knob (see Figure 20) clockwise
until you hear the “click” indicating that power has been turned
on. Look through the back of the reflex sight with both eyes
open to see the red dot. Position your eye at a comfortable
distance from the back of the sight. In daylight you may need
to cover the front of the sight with your hand to be able to see
Figure 17. The cast-metal dovetail trunnion on the left side panel
of the base mates with the left side bearing of the telescope tube.
Before mounting the tube on the base, turn the trunnion by hand so
that the hole for the tube connecting knob is facing up.
Threaded
hole for tube
connecting knob
Figure 19. Secure the tube to the base with the tube connecting
knob.
Figure 18. Hold the telescope tube as shown, with one hand on
the rear end ring and the other cradling underneath the tube, gently
lower the scope so the dovetail side bearing on the tube seats in the
metal trunnion on the left side panel.

9
the dot, which is purposefully quite dim. The intensity of the
dot is adjusted by turning the power knob. For best results
when stargazing, use the dimmest possible setting that allows
you to see the dot without difficulty. Typically a dimmer set-
ting is used under dark skies and a brighter setting is needed
under light-polluted skies or in daylight.
Aligning the EZ Finder II
When the EZ Finder II is properly aligned with the telescope,
an object that is centered on the EZ Finder II’s red dot should
also appear in the center of the field of view of the telescope’s
eyepiece. Alignment of the EZ Finder II is easiest during day-
light, before observing at night. Aim the telescope at a distant
object such as a telephone pole or roof chimney and center it
in the telescope’s eyepiece. The object should be at least 1/4
mile away. Now, with the EZ Finder II turned on, look though
the EZ Finder II. The object should appear in the field of view.
Without moving the main telescope, use the EZ Finder II’s
azimuth (left/right) and altitude (up/down) adjustment knobs
(see Figure 20) to position the red dot on the object in the
eyepiece. When the red dot is centered on the distant object,
check to make sure that the object is still centered in the
telescope’s field of view. If not, re-center it and adjust the EZ
Finder II’s alignment again. When the object is centered in
the eyepiece and on the EZ Finder’s red dot, the EZ Finder
II is properly aligned with the telescope. Once aligned, the
EZ Finder II will usually hold its alignment even after being
removed and remounted. Otherwise, only minimal realign-
ment will be needed. At the end of your observing session,
be sure to turn the power knob counterclockwise until it clicks
off. When the white dots on the EZ Finder II’s body and power
knob are lined up, the EZ Finder II is turned off.
Replacing the Battery
Should the battery ever die, replacement 3-volt lithium bat-
teries are available from many retail outlets. Remove the old
battery by inserting a small flat-head screwdriver into the slot
on the battery casing (Figure 20) and gently prying open the
case.Then carefully pull back on the retaining clip and remove
the old battery. Do not overbend the retaining clip. Then slide
the new battery under the battery lead with the positive (+)
end facing down and replace the battery casing.
Using Eyepieces
The final step in the assembly process is to insert an eye-
piece into the telescope’s focuser. First, take the cover cap
off the focuser drawtube. To use the 2" DeepView eyepiece,
loosen the two thumb screws on the 2" adapter (on the end
of the focuser drawtube) and remove the 1.25" adapter. Then
place the 2" eyepiece directly into the 2" eyepiece holder
and secure it with the two thumb screws loosened previously
(Figure 21). The other eyepiece and 1.25" adapter can be
placed in the eyepiece rack until they are needed.
To install the 1.25" Illuminated Plössl eyepiece instead of the
2" DeepView eyepiece, keep the 1.25" adapter in the focuser,
and make sure the two thumb screws on the 2" adapter are
tightened. Now, loosen the thumb screw on the 1.25" adapt-
er, do not loosen the two thumb screws on the 2" adapter.
Insert the 1.25" eyepiece into the 1.25" eyepiece adapter, and
secure it by retightening the thumb screw on the 1.25" eye-
piece adapter (Figure 21). The other eyepiece can be placed
in the eyepiece rack until it is needed.
The basic assembly of your SkyQuest XTg Dobsonian is now
complete. It should appear as shown in Figure 1. The dust
cap should always remain in place on the top of the tube sec-
tion 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
cap on the focuser when the telescope is idle.
Figure 20. The EZ Finder II reflex sight. Figure 21. Detail of the SkyQuest XTg 2" dual-speed focuser.
Power
knob
Altitude
adjustment
knob Thumbscrews Dovetail
mounting
bracket
Battery
casing
Azimuth
adjustment
knob
Drawtube tension setscrews
2" adapter
thumbscrews
1.25" adapter
thumbscrew
1.25" adapter
2" adapter
Focus lock
thumbscrew
Fine
focus
knob
Coarse
focus knob
Coarse
focus knob

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3. The GoTo
Hand Controller
The SkyQuest XTg features the SynScan AZ hand controller,
which provides two different modes of operation:
AutoTracking Mode
The SkyQuest XTg base incorporates a quad-encoder design
that records the position of the telescope relative to the sky.
In the AutoTracking mode, after a quick initial alignment pro-
cedure, you can move the telescope manually, or electroni-
cally by using the directional buttons on the hand controller,
to any position and the telescope will track the motion of the
sky, keeping your viewing target in the eyepiece field of view
indefinitely. Basically, this mode allows you to operate your
Dobsonian in the traditional way, with the added bonus of
automatic tracking.
GoTo Mode
GoTo mode provides automated, computerized object loca-
tion, i.e., “GoTo” functionality to assist you in finding and enjoy-
ing thousands of night sky objects such as planets, nebulas,
star clusters, galaxies, and more. You can slew the telescope
automatically to any of 42,000 celestial objects, or take a pre-
programmed tour the skies, with push-button simplicity. Once
the scope has pinpointed your desired observing target, the
telescope will track its motion, keeping it in the field of view.
Even inexperienced astronomers will find themselves quickly
mastering the variety of features the SynScan AZ GoTo sys-
tem offers in just a few observing sessions.
GoTo Hand Controller’s Features and Functions
The GoTo hand controller (Figure 22a) allows direct access
to all the motion controls of the telescope and a database
with some 42,000 pre-set objects.The controller comes with a
two-line, 16-character LCD screen that is backlit for comfort-
able viewing of the telescope information and scrolling text.
On the bottom end of the hand controller are three ports: a
wide RJ-45 port for the cable that connects the hand control-
ler to the GoTo base, an RJ-12 port that is used to connect
the hand controller to a PC (with provided RS-232 cable) for
firmware updates, and a DC power jack, which allows inde-
pendent use of the hand controller for browsing the database
or updating the firmware without connecting to the telescope
(Figure 22b).
NOTE: The DC power port on the hand controller is for
hand controller stand-alone applications only, such as
updating the firmware without connecting to the telescope.
For telescope operation, your 12V power source should be
plugged into the 12V DC port on the Dobsonian base.
There are four main categories of control buttons on the GoTo
hand controller (Figure 22a):
1) Mode buttons
2) Directional buttons
3) Scroll buttons
4) Dual purpose buttons
Mode Buttons
The three mode buttons are located at the top of the con-
troller, directly below the LCD display. They include the ESC,
ENTER, and SETUP buttons:
The ESC button is used to escape from a certain command or
go back a level in the menu tree.
The ENTER button is used to select the functions and sub-
menus in the menu tree, and to confirm certain functional
operations.
The SETUP button is a quick hot key that takes you to the
Setup submenu
Directional Buttons
The directional buttons allow the user to have complete
control of the telescope at almost any step in the operation.
These controls are locked out when the telescope is slewing
to an object. The directional buttons are very helpful for the
initial alignment of the GoTo system, for centering objects in
the eyepiece field of view, and for manually slewing the tele-
Display screen
Mode buttons
Directional buttons
Dual purpose buttons
Scroll buttons
Hand controller
RJ-45 port
Computer
interface
RJ-12 port
12V DC
power port
Figure 22. a) The SkyQuest XTg SynScan AZ hand controller’s
button layout, b) the bottom end of the hand controller.
a.
b.