Orion XT4.5 User Manual

IN 164 Rev.A

Providing Exceptional Consumer Optical Products Since 1975

Customer Support (800) 676-1343 E-mail: support@telescope.com

Corporate Offices (831) 763-7000 P.O. Box 1815, Santa Cruz, CA 95061

INSTRUCTION MANUAL

Orion

SkyQuest™ XT4.5

Dobsonian Reflector

#9804

Welcome to an exciting new world of adventure! Your SkyQuest XT4.5 Dobsonian is a high-quality opti-

cal 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 XT4.5 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, but it also serves as a guide for your first explorations in the sky. It is not necessary to immediately read the appendix sections at the end of the manual; they contain detailed information regarding aligning and cleaning the telescope’s optics, which should not be needed initially.

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

Focuser

Navigation Knob

Altitude Side Bearing

CorrecTension system

Eyepiece rack

Finder scope Finder scope

bracket

Eyepiece

Carry handle

Primary

mirror cell

Plastic foot

Figure 1. The SkyQuest XT4.5 parts diagram.

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 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 Optical tube Dust cover 1 25mm Sirius Plössl eyepiece, 1.25" barrel diameter 1 10mm Sirius Plössl eyepiece, 1.25" barrel diameter

1 Eyepiece rack w/mounting wood screws 1 6x26 Correct-Image finder scope w/O-Ring 1 Finder scope bracket 2 Spring coils 2 Pull loops 1 Collimation cap 4 Nylon spacers (black) 2 1/4" washers (black) 2 Phillips head screws (black, length 1-1/2")

Box #2: Dobsonian Base

Qty. Description 1 Left panel 1 Right panel 1 Front brace 1 Top baseplate 1 Ground baseplate 10 Base assembly screws 4 Trim caps (black) 3 Plastic feet 3 Feet attachment wood screws (length 3/4") 1 Self-adhesive rubber bumper 1 Large hex-head bolt (length 2") 2 3/8" washers 1 3/8" lock nut 1 Nylon spacer (white) 1 T-nut

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.

Table of Contents

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

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

3. Using Your Telescope........................................................................................................... 6

4. Observing Tips...................................................................................................................... 9

5. Astronomy Basics ................................................................................................................. 10

6. Care and Maintenance ......................................................................................................... 13

7. Specifications........................................................................................................................ 13

Appendix A: Collimation (Aligning the Mirrors)......................................................................... 14

Appendix B: Cleaning the Optics...............................................................................................15

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. The assembly process takes about 30 minutes and requires a Phillips screwdriver, and an adjustable crescent wrench. When tightening screws, tighten them until firm, but be careful not to strip the holes by overtightening. Children under the age of 12 should work with an adult.

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 four of the base assembly screws in the predrilled holes. The side panels should be oriented so the SkyQuest labels are facing outward. 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 four side screws installed earlier. Press a trim cap onto the heads of each of these screws.

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.

7. 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 bolt’s shaft. You might need to hold the bolt's 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. Over-tightening the lock nut (I) will make the mount difficult to rotate in the azimuthal (horizontal) direction.

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

Installing the Eyepiece Rack

The aluminum eyepiece rack holds three 1.25" eyepieces in a convenient place on the base, within easy reach while you're observing. A 1.25" barlow can also be held in the rack.

Figure 2. Exploded view of the Dobsonian base.

Figure 3. Position the rubber bumper “stop” over the index mark on the inside surface of the front brace.

You can install the rack so that it can be removed, or you can install it so it is permanently attached. About halfway down the left side panel of the base you will notice two predrilled starter holes, about 4" apart. Take the black wood screws that come packaged with the rack and thread them into the starter holes about three turns. Then you can “keyhole” the eyepiece rack onto the wood screws and continue tightening the screws. 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 hole. If you want to have the rack permanently attached, attach the screws tightly. (Figure 4)

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. The tube will not yet be properly balanced, since the CorrecTension system has not been installed. Keep the tube positioned upright, as shown in Figure 5, for now.

Installing the CorrecTension (XT) Friction Optimization System

To install the CorrecTension assembly, follow these steps while referring to Figure 6:

1. Put one of the black nylon spacers on a black Phillipshead 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 insert in the hole. Use a Phillips screwdriver to tighten the bolt. Repeat this procedure on the opposite side panel.

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 with the brass insert in 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 black 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 tube from the base, you will first need to disconnect the springs from the “posts” on the Dobsonian base. Remember to position the tube upright before doing this, or the tube will fall over. The springs will remain captive on the altitude side bearings, so they will not get lost.

Installing the Finder Scope

The SkyQuest XT4.5 comes with a high quality, 6x26 correctimage achromatic finder scope. (Figure 8a) The “6” means it magnifies 6 times, the “26” means it has a 26mm effective diameter lens, and the correct-image means the image in the finder scope will appear right side up, just like the view through your naked eye.

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.

Screw w/

round knob

Black nylon

spacers

1/4" washer

(black)

Pull loop

Spring

Altitude side bearing

Phillips head screw (black)

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.” Position the telescope as shown so that it won’t fall down before the CorrecTension System is installed and engaged.

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