Orion SKYQUEST #27182 XT6I, SKYQUEST #27184 XT10I, SKYQUEST #27189 XT12I, SKYQUEST #27183 XT8I User Manual


instruction Manual

Orion SkyQuestXTi

IntelliScope Dobsonian


#27182 XT6i, #27183 XT8i, #27184 XT10i, #27189 XT12i


Customer Support (800) 676-1343


E-mail: support@telescope.com


Corporate Offices (831) 763-7000


89 Hangar Way, Watsonville, CA 95076

Providing Exceptional Consumer Optical Products Since 1975



IN 226 Rev. I 08/11

Secondary mirror holder with 4-vane spider

(not visible)

Navigation knob

Retaining knob (opposite side)


Object Locator

Right side panel

Front brace

Eyepiece rack


Top baseplate

Ground baseplate

Finder scope

Finder scope bracket



Optical tube

Altitude tensioning knob

IntelliScope Controller Port modular jack

Primary mirror cell

Left side panel

Foot (3)

Figure 1. The SkyQuest XT8 IntelliScope


Congratulations on your purchase of an Orion SkyQuest XTi IntelliScope Dobsonian. It is a high-perfor- mance astronomical instrument designed to provide dazzling views of celestial objects and unprecedented ease of use. With the addition of the optional IntelliScope Computerized Object Locator (Controller), you gain the ability to locate and view thousands of celestial objects with the push of a button. Searching for faint objects – so often a source of frustration for telescope users – is a thing of the past, as the IntelliScope’s high-resolution digital encoders find them for you in seconds. It’s so easy!

Your SkyQuest IntelliScope will provide years of stargazing enjoyment, thanks to its large-aperture, precision optics; its innovative, user-friendly design; its complement of outstanding features and accessories; and most of all, its easy object locating technology. We hope you enjoy your journey through the universe!

Please read these instructions thoroughly before beginning assembly and subsequent use of the telescope.

Table of Contents


Unpacking. . . . . . . . . . . . . . .

. . . . 3


Assembly. .

. . . . . . . . . . . . .

. . . . 4

3. Using Your Telescope . . . . . . . . . . . . .


4. Alignment (Collimation) of the Optical System . . . . 15


Astronomical Observing . . . . . . . . .

. . . . 17

6. IntelliScope Computerized Object Location . . .

. . 20


Care and Maintenance . . . . . . . . . .

. . . 21

8. Specifications

. . . . . . . . . . . . . . . .


1. Unpacking

The telescope is packed in two boxes (three for the XT12i), one containing the optical tube assembly and accessories, the other containing the unassembled Dobsonian base (the third box for the XT12i includes the mirror and cell). Be careful 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.

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.

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.

Parts List

Box #1: Optical Tube Assembly and Accessories




Optical tube assembly


Dust cover


25mm Sirius Plössl eyepiece, 1.25"


10mm Sirius Plössl eyepiece, 1.25"

19x50 Right-angle correct-image finder scope (6x30 for the XT6i) with bracket

1 Collimation cap

14-Hole eyepiece rack (3-hole for XT6i)

2Eyepiece rack mounting screws

2 Tensioning/Retaining knobs

1 Tensioning knob nylon washer (white)

1 Tensioning knob metal washer


2Handle mounting hex-head screws

2Handle mounting screw washers

1Crescent wrench

1Azimuth encoder board

1Encoder connector board

1Azimuth encoder disk

Box #2: Dobsonian Base

Qty Description

1Left panel

1Right panel

1Front brace

1Top baseplate

1Ground baseplate

12Base assembly wood screws (length 2", black)

2Hex keys (4mm, 2mm)


Figure 1.2. To remove the rear end ring, unthread the screws that connect it to the tube.

Figure 1.3. Place the three springs on the exposed threaded shafts of the mirror cell.

Figure 1.4. 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.

3 Plastic feet

3Feet attachment wood screws (length 1")

5Encoder board mounting wood screws

1Brass bushing

1Azimuth axis hex-head screw (length 2.25")

2Fender washers (diameter 1")

1Hex lock nut

4Altitude bearing cylinders

4 Altitude bearing cylinder screws (length 1.5", black)

1 Vertical stop knob

1 Small thin Azimuth Encoder board washer

3 Vertical stop knob washers

Box #3 (XT12i only): Primary mirror and cell




Primary mirror


Mirror cell


Collimation knobs


Nylon washers



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 XT6i, XT8i, and XT10i are already installed inside the tube, so most of the required assembly concerns the Dobsonian base. Skip to “Assembly of the Dobsonian Base.” For the XT12i, the primary mirror is shipped in a separate box and will have to be installed in the optical tube. If you purchased the XT12i, start with the next paragraph for instructions on how to install the mirror into the tube.

Assembly of the Optical Tube (XT12i only)

In order to prevent damage to the primary mirror in shipment, it is shipped in its cell separately from the optical tube. To install the mirror cell into the optical tube, the rear end ring attached to the optical tube must first be removed. This is done by unthreading and removing the Phillips-head screws that connect the end ring to the tube (Figure 1.2), and then pulling the end ring off of 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 tube’s edge. Also be careful not to pinch your fingers when attaching the assembled mirror cell onto the tube.


Figure 1.5. Thread the collimation thumbnuts, with nylon washers attached, through the rear end ring and onto the threaded shafts. Make sure the thumbnuts have at least three full turns of engagement on the shafts.

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 1.3). Lower the end ring onto the mirror cell so the threaded shafts pass through it, and the end ring rests on the springs (Figure 1.4). Add a nylon washer to each collimation knob and thread the collimation knobs through the end ring and onto the threaded shafts (Figure 1.5). Make sure the knobs have at least three full turns of engagement on the shafts. The mirror cell is now ready to be installed into the tube.

Assembling the SkyQuest XT12i IntelliScope mirror cell to the tube can be a bit tricky. This is because the large diameter and thin aluminum of the tube will cause the tube to become somewhat out of round once the rear end ring is removed.

To assemble the mirror cell to the tube, stand the tube up vertically so that the raw edge of the tube is facing upward. 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 mirror cell onto the tube so that one side of the end ring is fully seated onto the tube (Figure 1.6). Now, look along the perimeter of the tube, and you will notice a bulge in the tube that prevents the mirror cell from fully seating on the tube (Figure 1.7). Position your body so that your chest is pressing against this bulge, and hug the telescope with your left hand so that the tube becomes round. With your right hand, gently tap down the side of the mirror cell that needs to be seated, and the entire mirror cell should seat onto the tube (Figure 1.8). Then replace the Phillips-head screws that connect the rear end ring to the tube.

Figure 1.6. Lower the assembled mirror cell onto the tube so one side of the end ring is seated on the tube edge. The threaded attachment holes in the end ring should also be lined up with the through holes in the end of the tube.

Figure 1.7. Locate the area of tube that is bulging out and preventing the mirror cell from fully seating.

Figure 1.8. Hug the tube so that your chest pushes against the bulge, and a gentle tap should fully seat the mirror cell onto the tube.























Figure 2. Exploded view of the XTi IntelliScope 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 45 minutes and requires, in addition to the supplied tools, a Phillips screwdriver, and two adjustable crescent wrenches.You can substitute a 7/16" crescent wrench for one of the adjustable crescent wrenches, or use a pair of pliers.

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.With a Phillips screwdriver, screw the plastic feet into the underside of the ground baseplate (A) using the self-tap- ping wood screws provided. 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 wrench to tighten the screws. The

Spacer washer

Figure 3a. The spacer washer goes between the azimuth encoder board and the top baseplate of the Dobsonian base.

Encoder board


mounting screw

Azimuth encoder board

Figure 3b. Installing the azimuth encoder board. Line up the large hole in the encoder board with the central hole in the top baseplate.

side panels should be oriented so the SkyQuest IntelliScope labels are facing outward. The front brace should be oriented so the threaded insert is facing the interior of the base. Do not completely tighten the screws yet.

3.Connect the two side panels (C) with the front brace attached to the top baseplate (D) with the remaining six base assembly screws in the predrilled holes. The side of the baseplate with the pilot hole near the square-shaped cutout should be facing downwards. Tighten all six screws firmly.

4.Tighten the six side screws installed earlier.

5.Attach the azimuth encoder board (E) to the underside of the top baseplate (D). Insert the encoder board mounting screw through the circuit board and install the small spacer washer (G) over the screw (Figure 3a). Insert the modular jack on the encoder board into the square-shaped hole in the baseplate and align the encoder board so that the small slotted hole in the board lines up with the predrilled starter hole, and the large hole lines up with the central hole in the baseplate. Thread the encoder board mounting screw into the predrilled starter hole with a Phillips screwdriver and tighten until just tight (Figure 3b).




Figure 4. To connect the baseplates, tilt them only slightly, as shown. Do not place them on their side. (a) Use one wrench to hold the hex nut steady (b) while turning the other end of the azimuth axis screw.

6.Place a fender washer (H) onto the azimuth axis screw (I). Then push the screw up through the hole in the ground baseplate (A).Then slide the encoder disk (J), flat side down, onto the azimuth axis screw.

7.Place the brass bushing (F) onto the azimuth axis screw

(I) so that the wide end of the bushing is closest to the encoder disk (J). Seat the bushing onto the encoder disk so that the registration feature on the bushing goes into the hole in the encoder disk. You may need to move the encoder disk around on the azimuth axis screw a bit for the bushing to seat properly.

8.Carefully position the top baseplate (D) over the ground baseplate (A) and lower it so the brass bushing (F) goes into in the center hole of the top baseplate. Place the remaining fender washer (K) onto the shaft of the azimuth axis screw, then thread the hex lock nut (L) onto the end of the azimuth axis screw and tighten it finger tight, for now.

9.To tighten the azimuth axis screw (I) and hex lock nut (L), tilt the assembled Dobsonian base at a slight angle to lift the ground baseplate off the ground. Now, with one wrench (or pliers) hold the head of the azimuth axis screw still while turning the hex lock nut with the other wrench. Figure 4 shows this being done. Tighten the hex lock nut just until the top fender washer is no longer moving freely,

Correct Tension pads

Bearing cylinders

Figure 5. Attaching the bearing cylinders.

Encoder connector board


Figure 6. Attaching the encoder connector board.

then tighten the hex nut a quarter turn beyond that. This ensures proper spacing between the encoder disk and the azimuth encoder board.

10.Attach the handle (M) to the front brace (B) with the two handle mounting hex-head screws. Place one washer on each screw, then press the handle against the front brace (the end of the handle bearing the Orion logo should be up). Then thread the screws from the inside of the base into the handle until tight using the supplied crescent wrench.

11.Line up one of the altitude bearing cylinders (N) with the inside of one of the four bearing cylinder holes on the side panels. Push a bearing cylinder screw through the side panel and thread the bearing cylinder onto it (Figure 5). The beveled end of the cylinder should be farthest from the side panel. You can tighten the cylinder by hand or, if needed, with the supplied 4mm hex key. Repeat for the remaining three bearing cylinders.

12.Attach the encoder connector board to the side panel. Place the board against the side panel so that the modular jack fits into the square-shaped hole and thread four encoder board mounting screws through the connector board and into the predrilled holes in the side panel until tight (Figure 6).


Next, you’ll need to install the altitude encoder board assembly. To do so, please refer to the separate instruction manual for the IntelliScope Computerized Object Locator.

Installing the Vertical Stop

Place three flat washers onto the shaft of the vertical stop screw. Thread the vertical stop into the threaded insert on the inside of the front panel until just tight (Figure 7). The position of the vertical stop is adjustable by adding or removing washers. This is important when using the IntelliScope Computerized Object Locator, since the optical tube must be exactly vertical before commencing with the two-star alignment procedure (described later). For precise adjustment of the vertical stop, see the manual for the Computerized Object Locator.

Installing the Eyepiece Rack

The aluminum eyepiece rack is a standard accessory on SkyQuest IntelliScope Dobsonians. It holds three 1.25" eyepieces and one 2" eyepiece (three 1.25" eyepieces on the XT6i) in a convenient place on the base, within easy reach while you’re observing. An optional 1.25" barlow lens also can be held in the rack. A few inches down from the top of the front brace panel you will notice two predrilled starter holes, about 6" apart. Thread the black wood screws 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 8). If you want to be able to remove the racklater without using a screwdriver, 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 opening of the keyhole. If you want to have the rack permanently attached, tighten the screws. You may find it easier to carry the base by the handle if the eyepiece rack is removed.

Placing the Optical Tube on the Dobsonian Base

Lift the optical tube and gently place it into the Dobsonian base so that the altitude bearings on either side of the tube rest on the bearing cylinders. Orient the optical tube as shown in Figure 9. Make certain that the optical tube does not get hung up on the vertical bumper stop or the CorrecTension pads as you put it in place. Be careful when placing the tube on the bearings, since if it is inserted at the wrong angle the hub can strike the encoder connector board and potentially damage it. Once on the bearing cylinders, the tube should pivot freely up and down with gentle hand pressure. Note that the tube will not yet be properly balanced, since the eyepiece and finder scope are not in place, and the CorrecTension system has not been installed.

Installing the CorrecTension Friction Optimization System

An exciting feature of the SkyQuest IntelliScope Dobsonians is the redesigned CorrecTension (XT) system. Because of their

Vertical Stop

Figure 7. The vertical stop

Figure 8. Using the two supplied wood screws, install the aluminum eyepiece rack in the predrilled holes near the top of the front panel.

relatively light weight, smaller Dobsonians (under 16") 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 telescope becomes very sensitive to balance, requiring additional equipment such as counterweight systems or springs to compensate.

SkyQuest IntelliScope Dobsonians employ a simple yet effective remedy for the friction problem that obviates the need for such cumbersome countermeasures. CorrecTension Friction Optimization utilizes a simple “disc brake” to apply the correct level of tension to the altitude bearings. With the XT system, 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 can be made equal to the azimuth friction, ensuring optimal navigation motion.


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