XT6, XT8, XT10

#9985, #9986, #9987


Customer Support (800)676-1343


E-mail: support@telescope.com


Corporate Offices (831) 763-7000

Providing Exceptional Consumer Optical Products Since 1975

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


IN 226 Rev. E 03/05

Secondary mirror holder with 4-vane spider (not visible)

Finder scope

Finder scope bracket



Navigation knob

Optical tube

Tensioning knob

IntelliScope Controller Port modular jack

Retaining knob (opposite side) Computerized Object Locator (optional)

Right side panel

Primary mirror cell

Eyepiece rack


Front brace



Left side panel

Top baseplate


Ground baseplate

Foot (3)


Figure 1. The SkyQuest XT8 IntelliScope


Congratulations on your purchase of an Orion SkyQuest XT IntelliScope Dobsonian. It is a high-perfor- manceastronomicalinstrumentdesignedtoprovidedazzlingviewsofcelestialobjectsandunprecedented 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 objects is a thing of the past, as the IntelliScope’s high-resolution digital encoders find them for you — in seconds. It’s so easy!

Even if you decide not to purchase the optional IntelliScope Controller, your SkyQuest telescope will provide years of stargazing enjoyment, thanks to its large-aperture, precision optics; its innovative, userfriendly design; and its complement of outstanding features and accessories. 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

1. Unpacking. . . . . . . . . . . . . . . . . . . . . . . . 3

2. Assembly . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Using Your Telescope . . . . . . . . . . . . . . . 8

4. Alignment (Collimation) of the

Optical System . . . . . . . . . . . . . . . . . . . 12

5. Astronomical Observing . . . . . . . . . . . . 14

6. Optional IntelliScope Computerized

Object Location. . . . . . . . . . . . . . . . . . . 17

7. Care and Maintenance . . . . . . . . . . . . . 17

8. Specifications . . . . . . . . . . . . . . . . . . . . 19

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.

1. Unpacking

The telescope is packed 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 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.

Parts List

Box #1: Optical Tube Assembly and Accessories

Qty. Description

1Optical tube assembly

1Dust cover

125mm Sirius Plössl eyepiece, 1.25" barrel diameter

110mm Sirius Plössl eyepiece, 1.25" barrel diameter

19x50 finder scope (6x30 for the XT6)

1Finder scope bracket with O-ring

1Collimation cap

14-Hole eyepiece rack (3-hole for XT6)

2Eyepiece rack mounting wood screws (length 3/4")

2Tensioning/Retaining knobs

1Tensioning knob nylon washer (white)

1Tensioning knob metal washer

1Nylon retaining knob spacer (black)


2Handle mounting hex-head screws

2Handle mounting screw washers 1 Crescent wrench

1 Azimuth encoder board

1 Encoder connector board

1 Encoder disk

Box #2: Dobsonian Base

Qty Description

1Left panel

1Right panel

1Front brace

1Top baseplate

1Ground baseplate

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

1Hex key (size 4mm)


3Plastic feet

3Feet attachment wood screws (length 1") 5 Encoder board mounting wood screws 1 Brass bushing

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

2 Fender washers (diameter 1")

1 Hex lock nut

4 Altitude bearing cylinders

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

1 Vertical stop knob

3Flat washers (2x1/16" thick, 1x1/32" thick)

(Please note: Unless otherwise specified, all images and pictures in this manual are of the SkyQuest XT8.)













Figure 2. Exploded view of the Dobsonian base.

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, 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.

The azimuth encoder board and other encoder items should be installed, even if you do not plan to use the optional Computerized Object Locator.The smooth motion of the telescope depends on the installation of these parts.

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 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.

Encoder board

mounting screw Azimuth encoder board

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

5.Attach the azimuth encoder board (E) to the underside of the top baseplate (D) (Figure 3). 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 an encoder board mounting screw into the predrilled starter hole with a Phillips screwdriver and tighten until just tight.

6.Place one 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 in order 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



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.

Correct Tension pads

Bearing cylinders

Figure 5. Attaching the bearing cylinders. (XT10 Shown)

just until the top fender washer is no longer moving freely, then tighten the hex nut a 3/16-1/4 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 with the 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 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 bearing cylinder. Then thread it into the built-in hex nut on the cylinder with a Phillips head screwdriver (Figure 5). The beveled end of the cylinder should be facing away from the side panel. Repeat this 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).

There are some predrilled holes on the side panel opposite the panel that holds the encoder connector board. These holes will be used to mount parts that come with the optional IntelliScope controller. If you purchased the IntelliScope controller with your SkyQuest, you will want to follow the installation instructions in the controller’s manual at this time.

Installing the Vertical Stop

Place the nylon spacer (white) and the 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 tight (Figure 7). The position of the vertical stop is adjustable by adding or removing washers.This is important when using the optional IntelliScope Computerized Object Locator, since the optical tube must be exactly vertical during the two-star alignment procedure.


Encoder connector board


Figure 6. Attaching the encoder connector board. (XT10 Shown)

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 XT6) 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. 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 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, 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

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

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.

Figure 9. Lift the optical tube and place it into the Dobsonian base so that the altitude bearings rest on the bearing cylinders. Orient the optical tube as shown. Do not bump the encoder connector board or vertical stop when installing the optical tube.

Installing the CorrecTension Friction Optimization System

An exciting feature of the SkyQuest IntelliScope Dobsonian is

the redesigned CorrecTension (XT) system. Because of their Vertical Stop 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.

Figure 7. The vertical stop


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