ORION TELESCOPES & BINOCULARS SkyQuest XT6 9806, SkyQuest XT8 9808 Instruction Manual

INSTRUCTION MANUAL

IN 165 Rev. B 09/03

Providing Exceptional Consumer Optical Products Since 1975

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

Corporate Offices [phone]
P.O. Box 1815, Santa Cruz, CA 95061

Orion

®

SkyQuest XT6&XT8

#9806 and #9808 Dobsonian Reflecting Telescopes

Secondary mirror with
4-vane spider (not shown)

Navigation knob

Right side panel

Front brace

Handle

Top baseplate

Ground baseplate

2

Figure 1.

The SkyQuest XT Dobsonian (XT6 pictured)

Finder scope

Finder scope bracket

Eyepiece

Focus knob

Optical tube

Altitude side bearing

CorrecTension Friction

Optimization System

Pull loop

Left side panel

Eyepiece rack

3

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.

Welcome to an exciting new world of adventure! Your

SkyQuest Dobsonian is a high-quality optical instrument
designed to bring you dazzling views of the outer reaches
of our universe.Easy enough for kids to use, and portable
enough for anyone to carry, the SkyQuest will provide fun
and entertainment for the entire family. Whether you are
brand-new to amateur astronomy or a seasoned stargaz­er, get ready for many evenings of enjoyment and
fascination. Before venturing into the night with your new
telescope, we recommend that you read through this
instruction manual.Not only does it provide accurate direc­tions for assembly and use, b ut it also serves as a guide for
your first explorations in the sky.

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 . . . . . . . . . . . . . . . . . .16

7. Specifications . . . . . . . . . . . . . . . . . . . . . . . . .17

1. Unpacking

The telescope will arrive in two box es, 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 below 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) 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, 1.25" barrel diameter
1 10mm Sirius Plössl eyepiece, 1.25" barrel diameter
1 6x30 finder scope

1 Finder scope bracket with O-ring
1 Collimation cap
1 Eyepiece rack
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 knob 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 (size 4mm)
3 Plastic feet
3 Feet attachment wood screws (length 1")
1 Self-adhesive rubber bumper
1 Large hex-head bolt (length 3")
2 3/8" washers
1 3/8" lock nut
1 Nylon spacer (white)
1T-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)

4

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-ter m
storage.The assembly process takes about 15 minutes and
requires a Phillips screwdriver, an adjustable crescent
wrench, and the provided hex keys.

Note: 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 provid­ed, 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 label is
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 assem­bly screws in the predrilled holes.Tighten all six screws.

4. Tighten the six side panel screws installed earlier.

5. Insert the white nylon bushing (E) into the hole in the cen­ter 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
bolt (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 panels attached)
over the ground baseplate and lower it so the bolt 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 bolts shaft.You might need to hold the bolts
head in place with another crescent wrench or pliers.
Tighten the lock nut with the 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 coming apart when moving
the telescope.

Note: Over tightening 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 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
bolts 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 surface 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 2. Exploded view of the SkyQuest XT Dobsonian base.

Figure 3. Position the rubber bumper “stop”over the index mark on

the inside surface of the front brace.

C

C

B

L

I

J

D

A

H
E

K

F
G

5

Figure 3. Press firmly so the adhesive holds the bumper
securely in place.

Installing the Eyepiece Rack

The aluminum eyepiece rack is a standard accessory on
SkyQuest Dobsonians. On the XT6 it holds three 1.25" eye­pieces in a convenient place on the base;on the XT8 it holds
three 1.25" eyepieces and one 2" eyepiece.These eyepieces
will be within easy reach while you’re observing.The rack will
also hold a 1.25" barlow lens.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 left­to-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 bal­anced, since the eyepiece and finder scope are not in place,
and the CorrecTension system has not been installed.

Installing the Finder Scope

The SkyQuest XT6 & 8 come with a high quality, 6x30 achro­matic finder scope (Figure 6a). The “6” means it magnifies 6
times, the “30”means it has a 30mm diameter lens.

To place the finder scope in the finder scope bracket, first
unthread the two black nylon screws until the screw ends are
flush with the inside diameter of the bracket.Place the O-ring
that comes on the base of the bracket over the body of the
finder scope until it seats into the groove on the middle of the
finder scope.Slide the eyepiece end (narrow end) of the finder
scope into the end of the bracket’s cylinder that does not have
the alignment screws while pulling the chrome, spring-loaded
tensioner on the bracket with your fingers (see Figure 6b).
Push the finder scope through the bracket until the O-ring
seats just inside the front opening of the bracket’s cylinder.
Now, release the tensioner and tighten the two black nylon
screws a couple of turns each to secure the finder scope in

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. (XT6 eyepiece rack shown)

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.”

Figure 6a. The 6x30 finder

scope.

Figure 6b. Inserting the

finder scope into the finder
scope bracket

Focus
lockring

Tensioner

Objective lens

Finder
Scope Bracket

Alignment thumbscrews

6

place.The tips of the tensioner and nylon screws should seat
into the wide groove on the rear of the finder scope’s body.

Slide the base of the finder scope bracket into the dovetail
holder near the focuser .Lock the bracket into position by tight­ening the knurled thumbscrew on the dovetail holder.

Installing the CorrecTension (XT) Friction
Optimization System

Perhaps the most exciting new feature of the SkyQuest
Dobsonians is the CorrecTension Friction Optimization sys­tem.Because of their light weight, 6" and 8" 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 telescope becomes very
sensitive to balance, requiring additional equipment such as
counterweight systems or adjustable side bearings to com­pensate.

SkyQuest 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 assembly 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 or solar filter 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 7:

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
cradle.The screw will thread into the preinstalled inser t in

the hole. Use a Phillips screwdriver to tighten the screw.
Repeat this procedure on the opposite side panel.

2. Next, insert one of the screws with a 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 alti­tude 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 posi­tion 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 8. You needn’t attach
both springs simultaneously; one at a time is fine.

Figure 7. Close-up view of the CorrecTension system, which

pulls the tube assembly down onto the altitude bearing pads.

Black nylon

spacers

1/4" washer

(black)

Altitude side bearing

Screw w/round knob

Spring
Phillips-head

screw (black)
Pull loop

Figure 8. (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 bolt head and onto the
narrow part of the nylon spacer, then release the pull loop.

a.

b.