Celestron G-3, G-5 User Manual

G-3 and G-5 Telescope

Models #11090 / #11091 / #11050/ #11051

CG-3 Equatorial Mount

Model #91503-A

INSTRUCTION MANUAL

¼"x20 Photo

Adapter

Mounting

Platform

Focuser Ring

Finderscope

Finder Bracket

Eyepiece

Star Diagonal

Mounting
Block

Photo Adapter Tightening Knob

Fig 1 – G-3 Optical tube

Corrector Plate

Mounting Bloc k

(G-5 Only)

¼" x 20 Photo Adapter

Mounting Platform (Used

for the G-3)

Declination Setting Circle

R.A. Locking Knob

R.A. Slow

Motion Knob

Counterweight

Optical Tube

Finderscope

Finder Bracket

Eyepiece

Star Diagonal

Declination Locking
Knob

Declination Slow
Motion Knob

Right Ascension
Setting Circle

Latitude Adjustment Knob

Counterweight

Locking Screw

Counterweight

Shaft

Counterweight Shaft

Safety Screw

R.A. Spur Gear

Figure 2 – The G-5 Telescope

Azimuth Adjustment
Knob

Tripod Leg

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INTRODUCTION

Congratulations on your purchase and welcome to the
to the hobby of astronomy, some of the terms and telescope components described in this instruction
manual may be new to you. This manual is designed to instruct you i n t he proper use of your Celestron G-3
and G-5 telescopes. To assist you in assembling and operating your telescope, take time to review this
manual and the parts diagram listed in Figures 1 & 2.

WARNING—NEVER LOOK AT THE SUN WITH YOUR TELESCOPE OR ITS FINDERSCOPE.
PERMANENT AND IRREVERSIBLE EYE DAMAGE MAY RESULT AS WELL AS DAMAGE
TO YOUR TELESCOPE.

HOWEVER, YOU MAY ENJOY LOOKING AT THE SUN IF YOU HAVE A SAFE METHOD OF
DOING SO—A SOLAR FILTER. IF USING A SOLAR FILTER, MAKE SURE THE
FINDERSCOPE IS COVERED.

Celestron

world of astronomy. If you’re a newcomer

TELESCOPE ASSEMBLY

The telescope and all items are packed in one box. Included are:

• Telescope Optical Tube

• German Equatorial Mount

• Adjustable Aluminum Tripod

• ¼" x 20 photo mounting platform (used for G-3 model)

• 6x30 Finderscope and Bracket (for G-5 models); 8x20 Erect Image Finderscope ( for G-3 models)

• Counterweight Shaft and Co unt erweights (2.2 Kg )

• Tripod Accessory Tray

• Declination Slow Motion Knob

• Right Ascension Slow Motion Knob

• 25mm SMA –1 ¼" Eyepiece

• 90º Star Diagonal – 1 ¼" (for G-5 Models); 90º Hybrid Diagonal – 1 ¼" ( for G-3 models)

• "The Sky" level I CD-ROM

• RA Motor Drive (for models #11091 & #11051)

Setting Up the Tripod:

The tripod legs come pre-assembled with the center leg support bracket attached to the inside of each tripod
leg. Each leg must then be attached to the tripod head of the equatorial mount.

1. Remove the tripod legs from their shipping box and place them horizontally on a flat surface.

2. Lie the metal tripod head on its side. Attach the three tripod legs one by one by sliding the bolt at the

top of each tripod leg into the slotted cut-outs located on the bottom of the tripod head. Tighten the
wing nuts on the end of the bolts to secure each tripod leg.

3. Stand the tripod with the tripod head attached on its feet and separate the tripod legs until the center

support bracket is fully extended.

Attaching the Accessory Tray

Next, attach the accessory tray to the tripod. Locate the accessory tray and the three wingnut screws to
attach the tray.

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1. Place the accessory tray on the center support brace of

the tripod and align the holes on the tray with those on
the support brace.

2. Insert the wingnut screws through the bottom of the

tripod support brace and thread them into the accessory
tray holes (See figure 3).

With the accessory tray in place, the tripod will be much
more stable, making it easier to attach the telescope.

Figure 3

Installing the Counterweight Bar

With the mount securely in place, you are ready to attach some of the accessories (the telescope tube will be
added last). Start with the Counterweight Bar and Counterweight. Used to balance the telescope, the
Counterweight Bar attaches to the opposite side of the mount as the telescope. To install the Counterweight
Bar:

1. Locate the exposed threads on the end of the Counterweight Bar.

2. Thread the Counterweight Bar into the declination shaft of the mount. It threads into the mount

opposite the telescope tube.

The Counterweight Bar is now installed.

Installing the Counterweight

With the counterweight bar in place, you are ready to attach the counterweight.

1. Remove the safety thumbscrew on the end of the counterweight bar.

2. Loosen the counterweight lock screw (on the counterweight itself) so that the central hole of the

counterweight is unobstructed.

3. Slide the counterweight onto the counterweight bar. Move it forward to the center of the

counterweight shaft.

4. Tighten the counterweight lock screw to hold it in position.

5. Replace the safety screw on the end of the counterweight bar. The thumbscrew will
prevent the counterweight(s) from sliding off the bar should they ever become loose.

Attaching the Slow Motion Knobs

1. A slow motion knob is provided for both the Right Ascension and Declination axis.

2. Locate the Right Ascension slow motion shaft (opposite of the chrome spur gear next to the R.A.

setting circle).

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3. Place the end of one of the slow motion knobs over the shaft and tighten the thumb screw on the
side.

4. Do the same for the declination slow motion shaft located just above the dec setting circle.

Attaching the Optical Tube (G-3 optical tube)

Before you attach the optical tube, make sure that the declination and right ascension locking knobs are
tight. The optical tube attaches to the mount via the ¼" x 20 photo mounting platform, which must be
attached to the top of the mount. To attach the photo mounting platform:

1. Locate the ¼" x 20 photo mounting platform.

2. Remove the two bolts from the bottom of the mounting platform.

3. Place the mounting platform on top of the telescope mount, aligning the holes with those on the

mount.

4. Insert the bolts from underneath the telescope mount and thread them back into the mounting

platform.

To mount the G-3 telescope tube:

1. Locate the square mounting block at the bottom of the G-3 optical tube. It will have a threaded
hole in the center of it for mounting to the tripod.

2. Place the optical tube over the photo mounting platform with the corrector plate end opposite of
the declination slow motion knob.

3. Align the threaded hole over the portion of the 1/4"x 20 bolt that is exposed above the mounting
platform.

4. Turn the black knob (located below the photo mounting platform) counterclockwise to secure the
optical tube to the mount.

Note: You may attach your optical tube to any heavy duty photo tripod (via the optical tube's mounting

block) if desired.

A

ttaching the Optical Tube (G-5 optical tube)

Before you attach the optical tube, make sure that the declination and right ascension locking knobs are
tight. The optical tube attaches to the mount via the mounting platform located at the top of the mount and
the mounting block attached to the bottom of the G-5 optical tube.

1. Locate the rectangular mounting b l ock at the bottom of the G-5 optical tube. It will have two
threaded holes used for mounting to the tripod.

2. Place the optical tube over the mounting platform with the corrector plate end opposite of the
declination slow motion knob.

3. Align the two threaded holes with the two holes on the top of the mounting platform.

4. Insert one of the mounting screws from the bottom of the mounting platform into the hole on the
opposite side of the declination slow motion knob. Only thread the screw about two rotations into
the optical tube's mounting block.

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5. Thread the second mounting screw into the hole nearest the declination slow motion cable. You
may wish to remove the slow motion knob in order to access the hole more freely. It may be
necessary to lift the optical tube slightly to allow the mounting screw to pass by the metal
declination indicator attached to the mount. Tighten both mounting screws.

Note: You may attach your optical tube to any heavy duty photo tripod (via the optical tube's mounting
block) if desired.

Now that the optical tube is secured to the mount, the optical tube accessories (finderscope, star diagonal
and eyepiece) can be attached.

Attaching the Finder Bracket to the Telescope

1. Locate the two holes in the rear cell of the telescope just left of the top of the tube (when looking
from the back of the tube).

2. Remove the tape covering the two holes. The tape prevents dust and moisture from entering the
optical tube before the finder is installed.

3. Place the finder bracket over the holes. The bracket should be oriented so that the ring with the
holes for the adjustment screws is closer to the rear cell (eyepiece end) of the telescope (see figures
1 & 2).

4. Thread the screws in by hand and then tighten with a screwdriver.

Attaching the Finder to the Bracket

With the bracket firmly attached to the telescope, you are ready to attach the finder to the bracket.

1. Thread the three screws into the finder bracket. Tighten the screws until the ends are flush with the
inner diameter of the bracket ring. Do not thread them in completely or they will interfere with the
placement of the finder.

2. Slide the rubber O-ring onto the back (eyepiece end) of the finder — it may need to be stretched a
little.

3. Position the O-ring on the main body of the finder so that it is toward the front (i.e., objective) end
of the finder.

4. Slide the finder, eyepiece end first, into the front ring of the bracket. Push it back until the O-ring
is snug inside the front ring of the bracket. For the G-3 te lescope, the 8x20 finder slides in
objective end first.

5. Hand tighten the three set screws until snug.

To align the finder, please see the next section on “Aligning the Finderscope.”

Aligning the Finderscope

Accurate alignment of the finderscope makes it easy to find objects with the telescope, especially celestial
objects. To make aligning the finderscope as easy as possible, this procedure should be done in the daytime
when it is easy to find and identify objects. To align the finder:

1. Choose a target that is in excess of one mile away. This will eliminate any possible parallax effect

between the telescope and finderscope.

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