Meade Etx 90Ec Users Manual

ETX-90EC to the manual f3344f30-6f43-4ac2-a36b-eec7057094b2

2015-02-05

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Instruction Manual
ETX-90EC Astro Telescope
ETX-125EC Astro Telescope

Meade Instruments Corporation

Features of the ETX-90EC
and ETX-125EC are identical,
with the exception of the siz e
of optical tube and the type
of viewfinder included as
standard equipment.

3
4
19

(on left
fork arm)

17
7
(on both sides)

16
8
9
21
15
14

13
10
12
11

Fig. 1: The ETX-90EC Astro Telescope.
1.
2.

Eyepiece
Viewfinder:
ETX-90EC: 8 x 21mm Erect-Image Viewfinder
ETX-125EC: 8 x 25mm Right-Angle Viewfinder
3. Eyepiece holder thumbscrew
4. 90° eyepiece holder
5. Optical tube: ETX-90EC: 90mm clear aperture
ETX-125EC: 127mm clear aperture
6. Vertical (or Declination) lock
7. Fork-mount attachment screws
8. Fork arm
9. Focus knob
10. Horizontal (or Right Ascension) lock

11. Computer control panel
12. Drive base
13. Hole cover for optional tripod legs (2)
14. Right Ascension (R.A.) setting circle
15. 1/4-20 photo tripod adapter block
16.Flip-mirror control knobs
17. Photo port
18. Declination (Dec.) setting circle (on left fork arm)
19. Viewfinder alignment screws
20. Viewfinder bracket
21. Electronic controller with attached coil cord

z
CONTENTS
WARNING!
Never use a Meade® ETX® Astro Telescope
to look at the Sun! Looking at or near the
Sun will cause instant and irreversible
damage to your eye. Eye damage is often
painless, so there is no warning to the
observer that damage has occurred until it
is too late. Do not point the telescope or its
viewfinder at or near the Sun. Do not look
through the telescope or its viewfinder as
it is moving. Children should always have
adult supervision while observing.

Quick-Start Guide . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Chapter 1: Getting Started . . . . . . . . . . . . . . . . . .5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
The Electronic Controller . . . . . . . . . . . . . . . . . .5
Parts Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Assembly Instructions . . . . . . . . . . . . . . . . . . . .5
Telescope Features . . . . . . . . . . . . . . . . . . . . . . . . .6
Quick Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Telescope Controls . . . . . . . . . . . . . . . . . . . . . .6
Computer Control Panel . . . . . . . . . . . . . . . . . . .6
Electronic Controller Functions . . . . . . . . . . . . . .6
First Observations . . . . . . . . . . . . . . . . . . . . . . .7
Observing with the Electronic Controller . . . .7
The Viewfinder . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Focusing the Viewfinder . . . . . . . . . . . . . . . . . . .8
Aligning the Viewfinder . . . . . . . . . . . . . . . . . . . .8
Using the Viewfinder . . . . . . . . . . . . . . . . . . . . .8

Chapter 2: Telescope Fundamentals
CAUTION: Use care to install batteries as
indicated by the battery compartment.
Follow battery manufacturers precautions.
Do not install batteries backward or mix
new and used batteries. Do not mix battery
types. If these precautions are not
followed, batteries may explode, catch fire,
or leak. Improperly installed batteries void
your Meade warranty.

. . . . . . . . .9
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Choosing an Eyepiece . . . . . . . . . . . . . . . . . . . .9
Understanding Magnification . . . . . . . . . . . . . . .9
Telescope Mountings . . . . . . . . . . . . . . . . . . . . .9
Terrestrial Observing . . . . . . . . . . . . . . . . . . . .10
Astronomical Observing . . . . . . . . . . . . . . . . . .10
Sidereal Rate . . . . . . . . . . . . . . . . . . . . . . .10
Slew Speeds . . . . . . . . . . . . . . . . . . . . . . .10
The Electronic Controller . . . . . . . . . . . . . . . . . . . .11
Modes of Operation . . . . . . . . . . . . . . . . . . . . .11
Using the Mode Screws . . . . . . . . . . . . . . .11
Electronic Controller Modes . . . . . . . . . . . .11

Chapter 3: Polar Alignment
If you are anxious to use your ETX Astro
Telescope for the first time, before a
thorough reading of this instruction manual,
see the Quick-Start Guide on page 4.

. . . . . . . . . . . . . . . .12
Celestial Coordinates . . . . . . . . . . . . . . . . . . . .12
Locating the Celestial Pole . . . . . . . . . . . . . . . .12
Polar Alignment Procedure . . . . . . . . . . . . . . . .12

Chapter 4: Observing

. . . . . . . . . . . . . . . . . . . . . .14
Objects in Space . . . . . . . . . . . . . . . . . . . . . . . . . .14
The Moon . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Planets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Deep-Sky Objects . . . . . . . . . . . . . . . . . . . . . .14
Photography with Both ETX Models . . . . . . . . . . . .15

Chapter 5: Optional Accessories . . . . . . . . . . .16
Chapter 6: Maintenance and Servicing . . . . .19
General Maintenance . . . . . . . . . . . . . . . . . . . .19
Storage and Transport . . . . . . . . . . . . . . . . . . .19
Inspecting the Optics . . . . . . . . . . . . . . . . . . . .19
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . .19
Meade Customer Service . . . . . . . . . . . . . . . . .20
Telescope Specifications . . . . . . . . . . . . . . . . .21

Appendix A: Tracking Motor Speed . . . . . . . .22
Appendix B: Helpful Charts . . . . . . . . . . . . . . . .23
Latitude Chart for Major Cities of the World . . .23
Star Locator . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Appendix C: Precise Polar Alignment;
Setting Circles . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
® The name “Meade,” the Meade logo, and “ETX” are
trademarks registered with the U.S. Patent Office and in
principal countries throughout the world. All rights reserved.
© 2000 Meade Instruments Corporation.

Precise Polar Alignment . . . . . . . . . . . . . . . . . .24
Setting Circles . . . . . . . . . . . . . . . . . . . . . . . . .24

Appendix D: Road Map to the Stars . . . . . . . .25
Appendix E: You and the Universe . . . . . . . . .26

z
QUICK-START
GUIDE

4
QUICKSTART
GUIDE

Remove the ETX from its packaging and place it on a
sturdy surface. Place the eyepiece (A) and viewfinder
(B) into their appropriate positions on the telescope
and tighten the appropriate attachment screws to a
firm feel only.

Flip the Power Switch (E) on the computer control
panel to the ON position. The lights flicker on the
Electronic Controller. Press any key and the motors
briefly move the telescope. The Electronic Controller is
now operational.

5
H

Slew Speed:
Fast
Medium
Moderate
Slow
I

Securely place the ETX on its side and remove the
battery compartment cover (C) from the underside of
the drive base. Insert eight (user-supplied) AA-size
batteries into the battery compartment (D) in the
proper orientation. Replace the cover and return the
telescope to an upright position.

NOTE:The
telescope has
rotational hard
stops in the
horizontal and
vertical axes to
prevent damage to
the telescope. See
Quick Tips, page 6,
for more
information.

Use the arrow keys (H) of the Electronic Controller to
move the telescope up and down and/or left and right.
To change the telescope’s slew speed, press the
SPEED key (I). The indicator lights signify the speed,
with the upper light showing the highest speed. Each
press slows the speed down one level, then cycles
back to the highest speed.

NOTE: Before
observing, verify
that the flip-mirror
control (16, Fig. 1) is
in the “up” position.
See Flip-Mirror
Control, page 6, for
more information.

E
Verify that the computer control panel power switch (E)
is in the OFF position. Remove the Electronic
Controller (F) from the packing materials and plug it
into the HBX port (G). Tighten the vertical and
horizontal locks (6 and 10, Fig. 1), then remove the
dust cover from the end of the telescope tube.

Sight along the side of the telescope’s main tube to
locate an object. Practice using the arrow keys on the
Electronic Controller to center an object in the
telescope’s field of view. Use the telescope’s focus
knob (9, Fig. 1) to bring the object into focus.

z STARTED
Chapter 1: GETTING
INTRODUCTION
A Meade ETXAstro Telescope is an extremely versatile, highresolution imaging system that, with advanced features similar
to larger and more specialized telescopes, can be used by
casual observers and serious astronomers alike. With
pushbutton controls, automatic tracking of celestial objects (with
one of the optional tripods), and diffraction-limited imaging, an
ETX telescope may be all the telescope ever required by many
terrestrial and astronomical observers.
As a first telescope, the ETX-90EC or ETX-125EC reveals
nature in an ever-expanding level of detail: observe the feather
structure of a bird from 50 yards or study the rings of the planet
Saturn from a distance of 800 million miles. Beyond the Solar
System observe nebulae, star clusters, galaxies, and other
deep-sky objects. Both telescopes are instruments fully capable
of growing with your interest.

Assembly Instructions

• ETX-90EC Astro Telescope
• ETX-125EC Astro Telescope

The Electronic Controller
Control of both ETX model telescopes is through pushbutton
operation of the standard-equipment Electronic Controller
(Fig. 2). Nearly all functions of the telescope are accomplished
through the Electronic Controller with just a few button pushes:
• Move the telescope on two axes
(up-and-down or left-and-right) at
any of 4 drive speeds for precise
tracking of astronomical or
terrestrial objects.
• Mount the telescope in the polar
mode for fully automatic tracking
of celestial objects using the
optional #880 (ETX–90EC), #881
(ETX-125EC) Table Tripod, or
#883 Deluxe Field Tripod (see
OPTIONAL ACCESSORIES, page
17).

CHAPTER

Assembly of both ETX model telescopes requires eight (usersupplied) AA-size batteries and the following steps:
1. a. ETX-90EC 8 x 21mm Viewfinder: Slide the eyepiece end
of the viewfinder through the front of the viewfinder
bracket (1, Fig. 3).

1
ETX-90EC Viewfinder

Your Meade ETX Astro Telescope is one of the most
revolutionary telescope systems ever developed. Read this
manual thoroughly to take full advantage of the telescope’s
numerous advanced features.
This manual provides instructions for the following products:

ETX-125EC Right-Angle Viewfinder

Fig.3: Installation of the Viewfinder.
b. ETX-125EC 8 x 25mm Right-Angle Viewfinder: Slide the
front cell end of the right-angle viewfinder through the rear
of the viewfinder bracket (2, Fig. 3).
You may need to unthread the six alignment screws slightly
to fit the viewfinder through the bracket. With the viewfinder
in place, tighten (to a firm feel only) the six alignment screws
against the viewfinder tube. To align the viewfinder, see page
8.
2. Remove the SP26mm eyepiece (1, Fig. 1) from its container
and place it in the eyepiece holder (4, Fig. 1). Tighten the
thumbscrew (3, Fig. 1) to a firm feel only.
3. The telescope’s battery compartment (6, Fig. 4) is at the
bottom of the drive base. Place the telescope securely on its
side as shown in Fig. 4. Open the battery compartment by
simultaneously depressing the two release latches (4, Fig. 4)
and pulling the battery cover (5, Fig. 4) away from the drive
base. Insert eight AA-size batteries into the battery
compartment, oriented as shown on the battery mounting
board. Put the cover back in place.
4. Place the telescope in an upright position on a flat surface.
Be certain that the power switch on the computer control
panel (1, Fig. 5) is in the OFF position. Plug the coil cord for
the Electronic Controller into the HBX port (3, Fig. 5).

• When in the polar mode, switch
the motor drive between northern
and Southern Hemisphere oper- Fig.2: Electronic
ation for observing from any- Controller.
where in the world.

1
2

A detailed description of the functions and operation of the
Electronic Controller is found in Electronic Controller
Functions, page 6.

Parts List
In keeping with the ETX philosophy of elegant simplicity, an ETX
telescope is virtually completely assembled at the Meade
factory. Getting the telescope ready for first observations
requires only a few minutes. When first opening the packing
box, note carefully the following parts:
•
•
•
•

The ETX Astro Telescope with fork-mount system.
Electronic Controller with attached coil cord.
Viewfinder, packed in a separate small box.
Super Plössl (SP) 26mm eyepiece, packed in a plastic
storage container, in a separate small box.
• Hex-wrench set (2 wrenches), packed with the manual.
The viewfinder is packed separately from the main telescope to
avoid the possibility of the viewfinder slipping in its bracket and
scratching the viewfinder tube during shipment.

3
6
4

5
Fig.4: Bottom view of an ETX showing eight AA-size
batteries mounted inside the battery compartment.
(1) High-latitude tripod leg hole; (2) Drive base;
(3) Alternate tripod leg hole; (4) Release latches;
(5) Battery compartment cover; (6) Battery compartment.
Basic assembly of either ETX model is now complete.

z
GETTING
STARTED

6
TELESCOPE FEATURES

CHAPTER

Quick Tips
• Rotational Limits: The telescope base and fork mount are
designed with internal “rotational limit stops.” The horizontal
limit stop prevents the telescope from rotating more than
630° to avoid damage to the internal wiring. The vertical limit
stop prevents the viewfinder from contacting the fork mount
when the telescope is pointed upward just past 90° and
prevents the optical tube from contacting the base if pointed
downward more than 30°. Do not force the telescope to
move be yond these stops or damage to the telescope will
result.
• Vertical Lock;Declination Setting Circle: The vertical lock
knob (6, Fig. 1) is a knurled knob located on the fork arm to
the right of the focus knob (9, Fig. 1). Mounted beneath the
knob is a circular scale with no numbers. Do not confuse this
scale with the Dec setting circle (18, Fig. 1) on the opposite
fork arm which has a number scale used to locate
astronomical objects.
• A Note on Indoor Viewing: While casual, low-power
observations may be made with the telescope through an
open or closed window, the best observing is always done
outdoors. Temperature differences between inside and
outside air and/or the low quality of most home window glass
can cause blurred images through the telescope. Do not
expect high-resolution imaging under these conditions.

Telescope Controls
An important array of features and manual controls facilitates
operation of an ETX telescope. Be sure to become acquainted
with all of these controls before attempting observations
through the telescope.
Horizontal Lock (10, Fig. 1): Controls manual horizontal
rotation of the telescope while sitting upright as shown in Fig.1.
Turning the horizontal lock counterclockwise unlocks the
telescope, enabling it to be freely rotated by hand about the
horizontal axis. Turning the horizontal lock clockwise prevents
the telescope from being rotated manually, but engages the
horizontal motor drive clutch for Electronic Controller operation.
When polar aligned, the horizontal lock serves as the Right
Ascension, or R.A. lock (see Right Ascension, page 12).
Vertical Lock (6, Fig. 1): Controls manual vertical movement of
the telescope while sitting upright as shown in Fig. 1. Turning
the vertical lock counterclockwise unlocks the telescope
enabling it to be freely rotated by hand about the vertical axis.
Turning the vertical lock clockwise (to a firm feel only) prevents
the telescope from being moved manually, but engages the
vertical motor drive clutch for Electronic Controller operation.
When polar aligned, the vertical lock serves as the Declination,
or Dec lock (see Declination, page 12).
Focus Knob (9, Fig. 1): Causes a finely-controlled internal
motion of the telescope’s primary mirror to achieve precise
image focus. An ETX can be focused on objects from a
distance of about 11.5 ft (ETX-90EC) or 15 ft (ETX-125EC) to
infinity. Rotate the focus knob clockwise to focus on distant
objects; counterclockwise to focus on near objects.
Flip-Mirror Control (16, Fig. 1): Both ETX models include an
internal optically-flat mirror. With the flip-mirror control in the
“up” position, as shown in Fig. 1, light is diverted at a 90° angle
to the eyepiece. Alternately, with the flip-mirror control in the
“down” position, light proceeds straight through the telescope
and out the photo port (17, Fig. 1) for telephoto or astronomical
photography using the optional #64 T-Adapter, or for observing
with the optional #932 45° Erecting Prism (see OPTIONAL
ACCESSORIES, page 17).

NOTE: The flip-mirror control is in the “up” position when the
control is vertical (perpendicular to the telescope tube). It is
“down” when the control is horizontal (parallel with the
telescope tube).

Computer Control Panel
The computer control panel (Fig. 5) of the ETX-90EC and
ETX–125EC models include a connector for either the
standard-equipment Electronic Controller or the optional #497
Autostar Computer Controller, an external power supply
connector, and two auxiliary ports (see OPTIONAL
ACCESSORIES, page 16).

Fig. 5: Computer Control Panel. (1) ON/OFF switch; (2)
Auxiliary ports; (3) Handbox port; (4) 12v connector; (5)
Power indicator light.
ON/OFF (1, Fig. 5): When the ON/OFF switch is moved to the
ON position, the red power indicator light (5, Fig. 5) illuminates
and power is supplied to the Electronic Controller and to the
telescope’s motor drive.
AUX (2, Fig. 5): Two identical auxiliary ports provide
connections for current and future Meade accessories.
CAUTION:Using products other than standard Meade
accessories may cause damage to the telescope’s
internal electronics and may void the Meade warranty.
HBX (3, Fig. 5): The HBX (handbox) port is designed to accept
the plug from the coil cord of the Electronic Controller or the
optional #497 Autostar Computer Controller.
12v (4, Fig. 5): The 12v connector is designed to accept an
external power supply such as the optional #541 AC adapter or
the #607 Power Cord (see OPTIONAL ACCESSORIES, page 18).
When one of these alternate powering options is used, the
internal batteries are disconnected from the power circuit.
NOTE: Always remove the batteries if they are not to be used
for a long period of time.

Electronic Controller Functions
The Electronic Controller provides the observer with the means
to control the telescope motors from a compact handbox. The
Electronic Controller (Fig. 6) has soft-touch keys designed to
have a positive feel, even through gloves.
Primary functions of the Electronic Controller are to move
(slew) the telescope, indicate the slew speed, and to operate
the optional #1244 (ETX-90EC) or #1247 (ETX-125EC) Electric
Focuser (see OPTIONAL ACCESSORIES, page 18). Other
functions are also possible when using the MODE key (see
Electronic Controller Modes, page 11 and APPENDIX A,
page 22).
Arrow Keys (1, Fig. 6): The four arrow keys slew the telescope
in four directions (i.e., up-and-down or left-and-right) at any one
of four slew speeds (see SPEED Key, page 7).
Important Note: While using the arrow keys to slew to an
object, when reversing direction there may be a slight
pause as the telescope motors compensate for the
reversal of the internal gears.

z
GETTING STARTED
Indicator Lights (2, Fig. 6): Four red LED (Light Emitting
Diode) lights are used to indicate the current slew speed.

any dew that might have collected during the observing session
has evaporated prior to replacing the dust cap.
With the standard-equipment SP 26mm eyepiece inserted in
the eyepiece holder, the telescope is operating at the following
power (see Understanding Magnification, page 9):
•
•

Fast

Medium

Moderate

Slow

4
Fig.6: Electronic Controller. (1) Arrow Keys; (2) Indicator
Lights; (3) SPEED Key; (4) Coil Cord; (5) MODEKey;
(6) OUT Key; (7) IN Key.
NOTE: For purposes of this manual, the lights are identified as
1 through 4, with 1 being the top light and 4 the bottom light.
Indicator Light Key
The procedures in this
manual identify the status of
the four indicator lights in a
box to the left of the appropriate step. They are depicted as on, blinking, or off,
depending on the mode at
that point.

Light No.

Light Status

Light 1

Light 2

Blinking

Light 3

Off

ETX-90EC
ETX-125EC

48X
73X

Objects viewed through the eyepiece are correctly oriented upand-down in the telescope but are reversed left-for-right. Image
orientation is discussed further in Terrestrial Observing,
page 10. The flip-mirror control (16, Fig. 1) must be in the “up”
position in order to observe an image through the telescope’s
eyepiece (see Flip-Mirror Control, page 6).
For the ultimate viewing experience, become familiar with the
features of your ETX telescope and the functions of the
Electronic Controller. Upon completing this chapter make first
observations of a simple land object several hundred yards in
the distance— perhaps a telephone pole or a building. Locate
objects first in the viewfinder before viewing them in the main
telescope (see Aligning the Viewfinder, page 8). Practice
focusing on the object using the focus knob (9, Fig. 1) and
centering the object in the eyepiece using the Electronic
Controller arrows keys (1, Fig. 6).

Observing with the Electronic Controller
With the Electronic Controller in the factory pre-set “Alt/Az”
(vertical-horizontal) mode, the Electronic Controller arrow keys
permit pushbutton movements (slewing) of the telescope. To
move the telescope using the Electronic Controller:
1. Set the telescope on a level and stable surface, or mount to
the Meade #883 Deluxe Field Tripod (see OPTIONAL
ACCESSORIES, page 17).
2. Insert a low-power eyepiece (e.g., SP 26mm) into the
eyepiece holder (4, Fig. 1) and tighten the eyepiece
thumbscrew (3, Fig. 1).

Light 4

SPEED Key (3, Fig. 6): The SPEED key is used to change the
speed at which the telescope slews when the arrow keys are
pressed. Each press of the SPEED key changes the slew
speed to the next slower setting. If the controller is already on
the slowest slew speed (light 4), pressing the SPEED key
cycles back to the highest speed (light 1). Slew speeds are
signified by the indicator lights (2, Fig. 6).

3. Tighten the vertical and horizontal locks (6 and 10, Fig. 1).
4. Verify that the power switch (1, Fig. 5) on the telescope’s
computer control panel is OFF.
5. Plug in the Electronic Controller coil cord (4, Fig. 6) to the
HBXport (3, Fig. 5) on the computer control panel.
6.

Flip the power switch to ON. The power indicator
light (5, Fig. 5) on the computer control panel
comes on and all four Electronic Controller
indicator lights (2, Fig. 6) blink rapidly.

Press any key on the Electronic Controller and the
telescope slews momentarily in the vertical and
horizontal directions to test the motors.

When the test is complete, light 1 comes on steady;
lights 2, 3, and 4 turn off.

Use the four arrow keys (1, Fig. 6) to slew the
telescope to the desired object. To change the slew
speed, press the SPEED key.

Fast
Medium
Moderate
Slow
MODE Key (5, Fig. 6): Pressing and holding the MODE key
puts the Electronic Controller into the Mode function (see
Electronic Controller Modes, page 11).
OUT Key (6, Fig. 6): The OUT key is used in conjunction with
the optional #1244 (ETX-90EC) or #1247 (ETX-125EC) Electric
Focuser (see OPTIONAL ACCESSORIES, page 18) to move the
focus point outward.
IN Key (7, Fig. 6): The IN key is used in conjunction with the
optional Electric Focuser to move the focus point inward.

First Observations
Unthread the metal dust cap from the front lens of the
telescope (counterclockwise), and the ETX may now be used
for terrestrial (land) observing.
NOTE:The dust cap should be replaced after each observing
session and the power turned off to the telescope. Verify that

10. Fine-adjust the position of the object with the
Electronic Controller arrow keys so that it is centered in the
viewfinder. The object is now ready to be viewed through the
telescope’s eyepiece.
Observing Tip: If the Electronic Controller has previously been
placed in the polar mode (see Electronic Controller Modes,
page 11) and Alt/Az operation is desired, flip the telescope
power switch to OFF and perform steps 6, 7, and 8 above. The
telescope is now in the Alt/Az mode. This procedure does not
work if one of the mode screws has been removed (see Using
the Mode Screws, page 11).

CHAPTER

z
GETTING
STARTED

8
THE VIEWFINDER

CHAPTER

As with most astronomical telescopes, both ETX model
telescopes present a fairly narrow field of view to the observer.
As a result it is sometimes difficult to locate and center objects
in the telescope’s field of view. The viewfinder, by contrast, is a
low-power, wide-field sighting scope with crosshairs that let you
easily center objects in the eyepiece of the main telescope’s
field of view.A telescope’s viewfinder is a tremendous aid in the
location of faint astronomical objects before observation is
made through the telescope’s eyepiece.
ETX-90EC 8 x 21 mm Erect-Image Viewfinder:
Standard equipment with the ETX-90EC, the 8 x 21mm ErectImage Viewfinder has 8-power magnification and an aperture
of 21mm. This viewfinder presents a correctly oriented image
both up-and-down and left-to-right.
ETX-125EC 8 x 25 mm Right-Angle Viewfinder:
Standard equipment with the ETX-125EC, the 8 x 25mm RightAngle Viewfinder has 8-power magnification and an aperture of
25mm. This viewfinder presents a correctly oriented image upand-down, but is reversed left-for-right.

telescope. Gently tighten the six alignment screws. Proceed
with Aligning the Viewfinder.
ETX-125EC
Turn the focus ring (2, Fig. 7) at the base of the viewfinder
eyepiece (3, Fig. 7) in either direction until a sharp focus is
reached.

Aligning the Viewfinder
In order for the viewfinder to be useful, it must first be aligned
with the main telescope, so that both the viewfinder and the
main telescope are pointing at precisely the same location. To
align the viewfinder follow this procedure:
1. The viewfinder bracket (5, Fig. 7) includes six alignment
screws (4 and 6, Fig. 7). Turn the three rear alignment
screws (6, Fig. 7) so that the viewfinder tube is roughly
centered within the viewfinder bracket.
NOTE: Do not overtighten the alignment screws. When
tightening one screw it may be necessary to loosen one or both
of the two other alignment screws .
2. Using the SP26mm eyepiece, point the main telescope at
some easy-to-find, well-defined land object, such as the top
of a telephone pole. Center the object precisely in the
eyepiece’s field of view, then tighten the vertical and
horizontal locks (6 and 10, Fig. 1) so that the object does not
move (1, Fig. 8).

3
2

4
ETX-125EC

(before
alignment)

1
5

ETX-90EC

Fig.7: The Viewfinder. (1) Front lens cell; (2) Knurled lockring (ETX-90EC) or focus ring (ETX-125EC); (3) Viewfinder
eyepiece; (4) Front alignment screws; (5) Viewfinder bracket;
(6) Rear alignment screws.

View through the
viewfinder

View through the
telescope eyepiece
(after
alignment)

Focusing the Viewfinder
Both ETX model viewfinders are factory pre-focused to objects
located at infinity. Individual eye variations may require that the
viewfinder be re-focused. To check the focus look through the
viewfinder. Point the viewfinder at a distant terrestrial (land)
object such as a telephone pole or light pole. If the viewfinder
image is not in sharp focus, follow the procedure for your type
of telescope.
ETX-90EC
1. If the viewfinder is mounted in the viewfinder bracket (5,Fig.
7), remove it by slightly unthreading the six alignment
screws (4 and 6, Fig. 7) until it can slip easily out of the
bracket.
2. Loosen the knurled lock-ring (2, Fig. 7) located near the
viewfinder’s front lens cell (1, Fig. 7). Unthread this ring
(counterclockwise, as seen from the eyepiece-end of the
viewfinder) by several turns.
3. Look through the viewfinder and focus on a distant object.
Slowly rotate the front lens cell in one direction or the other,
until the object appears sharp. One or two rotations of the
lens may have a significant effect on image focus.
4. Lock the focus in place by threading the knurled lock-ring
clockwise up against the viewfinder’s lens cell.
5. Place the viewfinder into the viewfinder bracket on the main

Fig.8: Aligning the Viewfinder.
3. While looking through the viewfinder, turn one or more of the
three front viewfinder alignment screws (4, Fig. 7), until the
crosshairs of the viewfinder point at precisely the same
position as the view through the eyepiece of the main
telescope (2, Fig. 8).
Re-check that the viewfinder’s crosshairs and the main
telescope are now pointing at precisely the same object. The
viewfinder is now aligned to the main telescope. Unless the
alignment screws are disturbed or the viewfinder jarred, the
viewfinder should remain aligned indefinitely.

Using the Viewfinder
To locate any object, terrestrial or astronomical, first center the
object in the crosshairs of the viewfinder; the object should also
then be centered in the field of view of the main telescope.
Observing Tip: If higher observing magnifications are
intended, first locate, center, and focus the object using a lowpower eyepiece (e.g., SP 26mm eyepiece). Remove the lowpower eyepiece and replace it with a higher-power e yepiece;
the object should still be centered in the field of view. Objects
are much easier to locate and center at lower powers; higher
powers are employed simply by changing eyepieces.

Chapter 2:TELESCOPE zFUNDAMENTALS
INTRODUCTION
Both ETX model telescopes can be used for immediate
observation right out of the box. However, becoming familiar
with the fundamentals of a telescope makes subsequent
viewing easier and more rewarding.

Choosing an Eyepiece
The function of a telescope’s eyepiece is to magnify the image
formed by the telescope’s main optics. Each eyepiece has a
focal length (expressed in millimeters, or “mm”). The smaller the
focal length, the higher the magnification. Low power eyepieces
offer a wide field of view, bright high-contrast images, and eye
relief during long observing sessions. To find an object with a
telescope it is always best to start with a low power eyepiece
such as the SP 26mm supplied with both ETX models. When
the object is located and centered in the eyepiece, switch to a
higher power eyepiece to enlarge the image as much as
practical for prevailing seeing conditions.
Lower power eyepieces are recommended for terrestrial
viewing. Haze, heat waves, and particulate matter in the air
distort images when using higher powers.
For astronomical observing a selection of several different
eyepieces is recommended. For general observing of the Moon
and planets, low to medium powers are preferred. For deep-sky
objects such as nebulae and galaxies, higher powers may be
needed for the best view if conditions permit.
NOTE: Viewing conditions vary widely from night to night.
Turbulence in the air, even on an apparently clear night, can
distort images. If an image appears fuzzy and ill-defined, back
off to a lower power eyepiece for a better resolved image (see
Fig.9).

Calculating Magnification: On a telescope, such as the ETX,
different eyepiece focal lengths are used to achieve different
magnifications, from low to high. The standard-equipment
SP 26mm eyepiece yields 48X (“48-power”) on the ETX-90EC
and 73X on the ETX-125EC. A variety of powers are obtainable
with the addition of optional eyepieces as well as the #126
2X Barlow Lens which double the power of the eyepiece
employed (see OPTIONAL ACCESSORIES, page 16).
Use this formula to calculate the magnification obtained with a
given eyepiece:
Telescope Focal Length
Power = ____________________
Eyepiece Focal Length
Example: The power obtained with the ETX-125EC using the
SP 26mm eyepiece is:
1900mm
Power = ________ = 73X
26mm
Too Much Power: The most common mistake of the beginning
observer is to overpower the telescope by using high
magnifications, which typical atmospheric conditions and the
telescope’s aperture cannot reasonably support. A smaller but
bright and well-resolved image is far superior to one that is
larger, but dim and poorly resolved (see Fig. 9). Powers above
300X (ETX–90EC) or 500X (ETX–125EC) should be employed
only under the steadiest atmospheric conditions.
Most observers should have 3 or 4 eyepieces plus the #126 2X
Barlow Lens to achieve the
full range of reasonable
magnifications
possible
with both ETX models.

Understanding Magnification
The magnification, or power, at which a telescope is operating is
determined by two factors: the focal length of the telescope and
the focal length of the e yepiece employed.
Telescope Focal Length is the distance that light travels inside
the telescope before reaching a focus. In the mirror-lens design
of both ETX models, however, this focal length is, in effect,
compressed by the telescope’s secondary mirror, so that a long
effective focal length is housed in the short ETX optical tube. For
example, the ETX-90EC’s focal length is 1250mm, or about 49”.
This means that if the ETX–90EC were a classical refractingtype of telescope, its optical tube would be more than four feet
long instead of the ETX–90EC's compact 11” tube length.
Eyepiece Focal Length is the distance light travels inside the
eyepiece before reaching focus. Focal length is usually printed on
the side of the eyepiece. Both ETX models are supplied with at
least one eyepiece as standard-equipment. For instance, the
Super Plössl (SP) 26mm eyepiece supplied with the ETX-90EC
and ETX-125EC has a focal length of 26mm. “Super Plössl”
refers to the optical design of the eyepiece, a design specifically
intended for high-performance telescopes and one which yields a
wide, comfortable field of view with extremely high image
resolution.

The telescope mounting or mount is the mechanical means that
causes the telescope’s optical tube to move in various
directions. Telescope mounts are of two basic types.

Technical note to the advanced amateur astronomer: The
SP 26mm eyepiece supplied with the Meade ETX-90ECand
ETX-125EC is a special low-profile version of the standard
Meade SP 26mm eyepiece which is about 1/4” (6mm) shorter
than the standard eyepiece. This low-profile SP 26mm is
designed to harmonize with the ultracompact scale of both ETX
models and utilizes the exact same optics as the standard SP
26mm eyepiece. The SP 26mm low-profile eyepiece is not
parfocal with other eyepieces in the SP series (i.e., the eyepiece
requires re-focusing when it is interchanged with other SP
eyepieces).

Altazimuth (Alt/Az) mounts permit motion of the telescope
tube in vertical (altitude) and horizontal (azimuth) directions.
Both ETX models incorporate an altazimuth mount (as shown in
Fig. 10). For all terrestrial applications and for casual
astronomical observing, the telescope operates very well in the
altazimuth configuration. The telescope may be placed on a
rigid tabletop or on the optional Meade #883 Deluxe Field Tripod
(see page 17) to provide a secure, variable-height, altazimuth
observing platform. To track objects, either terrestrial or
astronomical, with the telescope in the altazimuth configuration,
press the arrow keys of the Electronic Controller (see page6).

Fig.9: Example of too much magnification (Galaxy M51).

Telescope Mountings

9
CHAPTER

z FUNDAMENTALS
TELESCOPE

surface through heat waves. These heat waves often degrade
image quality. Low-power eyepieces, like the SP26mm eyepiece,
magnify these heat waves less than higher-power eyepieces.
Therefore, low-power eyepieces provide a steadier, higherquality image. If the image is fuzzy or ill-defined, reduce to a
lower power. Observing in early morning hours, before the
ground has built up internal heat, produces better viewing
conditions than during late-afternoon hours.

CHAPTER

Astronomical Observing
Fig. 10: Alt/Az mounting moves the telescope in vertical and
horizontal directions.
Equatorial mounts are highly desirable in the operation of any
telescope used for extensive astronomical applications, because
celestial objects do not move in vertical or horizontal directions
but in a combination of these directions. By tilting one of the
telescope’s mechanical axes (see Fig. 11) to point at the
celestial pole (i.e., by pointing one axis of the telescope to the
North Star, Polaris), you may follow (track) astronomical objects.

Used as an astronomical instrument, either ETX model has
many optical and electromechanical capabilities. In astronomical
applications, the extremely high level of optical performance of
both ETX telescopes is readily visible. The range of observable
astronomical objects is, with minor qualification, limited only by
the observer’s motivation.

Sidereal Rate
As the Earth rotates beneath the night sky, the stars appear to
move from East to West. The speed at which the stars move is
called the sidereal rate.

Never use a Meade ETX Astro Telescope to look at the
Sun! Looking at or near the Sun will cause instant and
irreversible damage to your eye. Eye dama ge is often
painless, so there is no warning to the observer that
damage has occurred until it is too late. Do not point
the telescope or its viewfinder at or near the Sun. Do
not look through the telescope or its viewfinder as it is
moving.Children should always have adult supervision
while observing.

Fig. 11: Equatorial mounting aligns the telescope with the
celestial sphere.
You need to turn in only one axis of the telescope instead of
simultaneously turning in two axes, as required of the altazimuth
mount. An equatorial mount which has one of its axes (the polar
axis) pointing to the celestial pole is polar aligned. Both ETX
models can be polar aligned either by using the optional #883
Deluxe Field Tripod or the table tripod specific to your model of
ETX telescope (see OPTIONAL ACCESSORIES, page 17).
With the ETX polar aligned (see page 12) the telescope’s
internal motor drive may be activated (see Modes of Operation,
page 11) to enable fully automatic hands off tracking of celestial
objects. In this configuration the observer does not need to press
the arrow keys of the Electronic Controller in order to track
celestial objects. Notwithstanding this automatic tracking, the
arrow keys of the Electronic Controller are useful in this
configuration to enable the centering of objects within the
telescopic field or, for example, to rove the telescope over the
surface of the Moon or through a large star field.

Terrestrial Observing
Both ETX models make excellent, high-resolution terrestrial
(land) telescopes. When you set the telescope on its drive base,
as shown in Fig. 1, you may use it for an extremely wide range
of observations. However, terrestrial images are right-side-up,
but reversed left-for-right when viewed through the eyepiece.
Normally, such an image orientation is not bothersome, unless
you are trying to read a distant sign, for example. If the telescope
is to be used for extensive terrestrial observations, a fully
correctly oriented image is provided with the #932 45° Erecting
Prism (see OPTIONAL ACCESSORIES, page 17).
Viewing terrestrial objects requires looking along the Earth's

If the telescope is polar aligned (enabled by mounting the
telescope to one of the optional tripods), the motor drive in each
ETX model is designed to rotate the telescope at the sidereal
rate so that it automatically tracks the stars. This tracking makes
it easy to locate objects and keep them centered in the
telescope’s eyepiece.

Slew Speeds
The Electronic Controller has four slew speeds that are directly
proportional to the sidereal rate. These speeds are signified by
the Electronic Controller indicator lights (2, Fig. 6) and have
been calculated to accomplish specific functions.
Light 1: The fastest slew speed moves the telescope quickly
from one point in the sky to another.
Light 2: The next fastest speed is best used for centering the
object in the viewfinder.
Light 3: The third speed is set to enable centering the object in
the field of a low-to-moderate power eyepiece, such as the
standard SP26mm.
Light 4: The slowest slew speed is for centering an object in the
field of view of a high-power eyepiece (e.g., 200X to 300X for the
ETX-90EC or 400X to 500X for the ETX-125EC).
The four available speeds are:
Light 1 = 1200 x sidereal (300 arc-min/sec or 5°/sec)
Light 2 =

180 x sidereal (45 arc-min/sec or 0.75°/sec)

Light 3 =

32 x sidereal (8 arc-min/sec or 0.13°/sec)

Light 4 =

8 x sidereal (2 arc-min/sec or 0.034°/sec)

The two slowest speeds (8x and 32x sidereal) should be used
for pushbutton tracking of astronomical objects while observing
through the eyepiece.

z
TELESCOPE FUNDAMENTALS
THE ELECTRONIC CONTROLLER
Briefly described on page 6, the Electronic Controller is the
primary device used to move ETX model telescopes. Electronic
Controller functions include:
• Slewing the telescope (see Observing with the Electronic
Controller, page 6)
• Turning on the telescope motor drive to automatically track
celestial objects (when the telescope is polar aligned)
• Changing the hemisphere of operation, when required
• Changing tracking speed (see APPENDIX A, page 22)

Modes of Operation
The Electronic Controller can be set to operate in either of two
primary modes: the Alt/Az mode (used when the telescope is
operated in the altazimuth configuration; see page 9) and the
polar mode (used when the telescope is polar-aligned; see page
10).
• Alt/Az (altitude-azimuth, or vertical-horizontal) mode should
be chosen for all terrestrial operations of the telescope. In the
Alt/Az mode you can use the arrow keys to slew the
telescope to terrestrial or astronomical objects and, once you
locate them, you can follow these objects if they move.
However, in this mode astronomical tracking is not automatic
and requires continuous key pushes. The Electronic
Controller is factory pre-set to the Alt/Az mode.
• Polar mode should be chosen in cases where the telescope
is equipped with either the optional #880 (ETX–90EC) or #881
(ETX-125EC) Table Tripod, or #883 Deluxe Field Tripod,
permitting polar alignment of the telescope for extensive
astronomical observations. In this mode you can use the
arrow keys to slew the telescope to objects, as in the Alt/Az
mode above. In addition, the telescope’s internal motor drive
is turned on, enabling fully automatic tracking of celestial
objects.

Electronic Controller when power is applied (i.e., the motor drive
is activated for operation in the Earth’s Northern Hemisphere —
the U.S.A., Europe, Japan, etc.).
Mode Screw B (2, Fig. 12): Remove mode screw B to to make
the Southern Hemisphere polar mode the automatic default of
the Electronic Controller when power is applied (i.e., the motor
drive is activated for operation in the Earth’s Southern
Hemisphere — Australia, South America, Africa, etc.).
NOTES:(1) Leaving both A and B screws in place (or removing
both screws) keeps the telescope in its original Alt/Az mode.
(2) Removing either A or B screw affects only the telescope’s
default mode; you may still make mode changes at will during
telescope operation using the MODE key (see Electronic
Controller Modes, below).

Electronic Controller Modes
The Electronic Controller is in the Alt/Az mode when activated,
unless a mode screw has been removed. To use the Electronic
Controller to change to Northern or Southern Hemisphere polar
mode, or to use Alt/Az mode with one of the mode screws
removed, use the following procedure:
1.

Complete the Polar Alignment Procedure on page 12.

Complete steps 2 through 8 in Observing with the
Electronic Controller (page 7) to initialize the Electronic
Controller.
3.

Press and hold the MODE key (5, Fig. 6) until lights
1 and 2 are on steady and lights 3 and 4 start
blinking.

Press the SPEED key (3, Fig. 6) once. This changes
the system to polar mode for the Earth’s Southern
Hemisphere, with the motor drive set to operate at
the sidereal rate.

Press the SPEED key a second time. This changes
the system to polar mode for the Earth’s Northern
hemisphere, with the motor drive set to operate at
the sidereal rate.

Press the SPEEDkey a third time and the system
returns to the Alt/Az mode. In the Alt/Az mode the
motor drive does not activate when exiting from the
Mode function.

Use the SPEED key as described in the above
steps to cycle among these three modes (Alt/Az,
Southern Hemisphere polar, or Northern Hemisphere polar) until the desired mode is shown by the
appropriate light configuration.

Press and hold the MODEkey until just one light is
on. This exits the Mode function. If you choose
Northern or Southern Hemisphere polar mode, the
motor drive starts operating at the sidereal rate.

Use the four arrow keys (1, Fig. 6) to slew the
telescope to the desired object. To change the slew
speed, press the SPEED key.

The following two methods are available to change the
Electronic Controller between the Alt/Az and polar modes:
1. Physically remove one of the mode screws (see Using the
Mode Screws, below).
2. Use the MODE key on the Electronic Controller, as described
in Electronic Controller Modes, opposite.

Using the Mode Screws
You can remove the two screws on the bottom rear of the
Electronic Controller handbox to change the default mode of the
Electronic Controller to Alt/Az or polar and, if polar, to the
hemisphere in which you are located.
NOTE:Mode screws A and B are the outer screws in the recess
directly under the letters A and B on the rear of the Electronic
Controller. Do not remove either of the inner two screws in the
recess.

Fig.12: Mode screws on rear of Electronic Controller.
(1) Mode .screw A; (2) Mode screw B.
Mode Screw A (1, Fig. 12): Remove mode screw A to make the
Northern hemisphere polar mode the automatic default of the

NOTE: See APPENDIX A (page 22) for advanced
functions of the Electronic Controller.

11
CHAPTER

Chapter 3: POLAR ALIGNMENT

12
APTER

For extensive astronomical observing, the telescope is best
mounted in the polar configuration. In polar alignment the
telescope is oriented so that the horizontal and vertical axes of the
telescope align with the celestial coordinate system (see Fig. 11).
To polar align either ETX model you must understand how and
where to locate celestial objects as they move across the sky. This
section introduces the terminology of polar-aligned astronomy,
and includes instructions for finding the celestial pole and for
following objects in the night sky using Declination and Right
Ascension.

Just as in mapping the surface of the Earth, imaginary lines have
been drawn to form a coordinate grid for the celestial sphere.
Object positions on the Earth’s surface are specified by their
latitude and longitude. For example, you could locate Los
Angeles, California, by its latitude (+34°) and longitude (118°).
Similarly, you could locate the constellation Ursa Major, which
includes the Big Dipper, by its general position on the celestial
sphere:
Right Ascension: 11hr; Declination: +50°.
• Right Ascension: The celestial analog to Earth longitude is
Right Ascension (R.A.). It is measured in time on the 24-hour
clock and shown in hours (hr), minutes (min) and seconds (sec)
from an arbitrarily defined zero line passing through the
constellation Pegasus. R.A. coordinates range from 0hr 0min
0sec to 23hr 59min 59sec. Thus there are 24 primary lines of
R.A., located at 15-degree intervals along the celestial equator.
Objects located further and further east of the prime R.A. grid
line (0hr 0min 0sec) carry higher R.A. coordinates.

ALT/AZ:
Tripod head
locked at 90°

POLAR:
Tripod head
locked at
observer’s
latitude

• Declination: The celestial analog to Earth latitude is called
Declination (Dec.). It is measured in degrees, minutes, and
seconds (e.g., 15° 27' 33"). Dec. shown as north of the celestial
equator is indicated with a plus (+) sign (e.g., the Dec. of the
North celestial pole is +90°). Dec. south of the celestial equator
is indicated with a minus (–) sign (the Dec.of the South celestial
pole is –90°). Any point on the celestial equator (which passes
through the constellations Orion, Virgo, and Aquarius) is
specified as having a Declination of zero, shown as 0° 0' 0".

Fig. 13: Examples of Alt/Az and polar mounting of an
ETX-90EC to the optional #883 Deluxe Field Tripod.

All celestial objects are specified in position by their celestial
coordinates of R.A. and Dec.

Locating the Celestial Pole

Celestial Coordinates
Celestial objects are mapped according to a coordinate system on
the celestial sphere (Fig. 14), an imaginary sphere surrounding
Earth on which all stars appear to be placed. This celestial object
mapping system is analogous to the Earth-based coordinate
system of latitude and longitude.

To get basic bearings at an observing location, take note of where
the sun rises (East) and sets (West) each day. After the site is
dark, face north by pointing your left shoulder toward where the
sun set. To precisely point at the pole, find the North Star (Polaris)
by using the Big Dipper as a guide (Fig. 17).

Polar Alignment Procedure
1

As the Earth rotates once on its axis every 24 hours, astronomical
objects appear to move across the sky in an arc. This apparent
motion (see Sidereal Rate, page 10) is not obvious to the unaided
eye, but viewed through a serious telescope such as the ETX90EC or ETX-125EC, this motion is rapid indeed. If the motor
drive has not been engaged, objects centered in the telescope’s
eyepiece move entirely out of the field of view in 30 to 160
seconds, depending on the magnification employed.
For easy tracking of astronomical objects your ETX telescope
should be polar aligned.
There are two mounting methods available to polar align the
telescope: the optional #883 Deluxe Field Tripod or the table
tripod specific to your model of ETX telescope.

Fig.14: The Celestial Sphere.
The poles of the celestial coordinate system are defined as those
two points where the Earth’s rotational axis, if extended to infinity,
north and south, intersect the celestial sphere. Thus, the North
Celestial Pole (1, Fig. 14) is that point in the sky where an
extension of the Earth’s axis through the North Pole intersects the
celestial sphere. This point in the sky is located near the North
Star, Polaris.
In mapping the surface of the Earth, lines of longitude are drawn
between the North and South Poles. Similarly, lines of latitude are
drawn in an east-west direction, parallel to the Earth’s equator.
The celestial equator (2, Fig. 14) is a projection of the Earth’s
equator onto the celestial sphere.

To Polar align using the #883 Deluxe Field Tripod (Fig. 13), follow
the instructions provided with the tripod. To Polar align using the
#880 (ETX-90EC) or #881 Table Tripod (ETX–125EC), use the
following procedure.
1. Make sure the viewfinder is aligned with your ETX telescope
(see Aligning the Viewfinder, page 8).
2. Remove the two hole covers (13, Fig. 1) from the side of the
drive base and thread the two identical fixed legs (4, Fig. 16)
into these holes to a firm feel only.
3. Determine the latitude of the observing location from a road
map, atlas, or the Latitude Chart for Major Cities of the
World, page 23; determining the latitude within about one
degree is sufficient.

POLAR ALIGNMENT
4. Each table tripod is equipped with two
adjustable tripod legs: The standard tripod
leg is used at observing latitudes as shown in
the box in step 5 and has a dual latitude label
attached (Fig. 15). The high-latitude tripod
leg is shorter and is used at higher observing
latitudes. Based on the observing latitude
determined in step 3, set aside the tripod leg
that is not to be used.
5. Locate the two mounting holes on the bottom
of the telescope drive base. Mount the
appropriate adjustable tripod leg (as
determined in step 4) to the drive base using
the following latitudes:
Standard Tripod Leg (ETX-90EC)
32.5° to 48.5° uses high-latitude hole
(2, Fig. 16).
22° to 35.5° uses alternate hole
(3, Fig. 16).
High-Latitude Tripod Leg (ETX-90EC)
56° to 66° uses high-latitude hole.
44° to 55° uses alternate hole.
Standard Tripod Leg (ETX-125EC)
33.5° to 49.5° uses high-latitude hole.
23.25° to 36.5° uses alternate hole.
High-Latitude Tripod Leg (ETX-125EC)
56.6° to 67° uses high-latitude hole.
44.5° to 56.5° uses alternate hole.
Thread the appropriate leg into the required
hole to a firm feel only.
6. A small thumbscrew (6, Fig. 16) is attached to
both the standard and high-latitude tripod
legs. Loosening the thumbscrew allows the
outer section of the leg to slide over the inner
section, so that the leg can be extended. If
using the standard tripod leg, extend the leg
so that the center of the thumbscrew head
aligns with the latitude of the observing
location on the scale. Retighten the
thumbscrew to a firm feel. (If using the highlatitude tripod leg, complete the adjustment of
the leg extension in step 9.)
Example: The latitude of New York City is 41°.
The tripod leg should be extended so that the
center of the thumbscrew is set next to the 41° Fig.15:
Example of
reading on the scale.
Standard Tripod
CAUTION:When using the #880 Table Tripod Leg Latitude
with the ETX-90EC, the optional #1422 Low- Scales.
Latitude Balance Weight is recommended if
the telescope is to be polar aligned below 30°, or if heavy
accessories are attached to the eyepiece-end of the
telescope. The low-latitude balance weight is recommended
for the ETX-125EC at all observing latitudes and is included
as standard equipment with the #881 Table Tripod.
NOTE:With the standard tripod leg threaded into the appropriate
hole in the drive base, the latitude scale may be at an
inconvenient position for reading (e.g., the scale faces the drive
base). This situation can be remedied by unthreading the leg,
removing the thumbscrew, rotating the inner leg 180°, then
reinserting the thumbscrew. The scale should now be readable
when threaded back into the telescope base.
7. Loosen the vertical and horizontal locks (6 and 10, Fig. 1) and
rotate the telescope so that it is oriented as shown in Fig. 16.
Tighten the vertical and horizontal locks. In this orientation the
telescope’s optical tube is lined up parallel to the tripod’s
adjustable leg.

CHAPTER

3
7
8

2
5

Dec.at 90°

3
4

Fig.16: Example of Polar Alignment Using the #880 Table
Tripod and ETX-90EC. (1) Standard tripod leg with latitude
scale; (2) High-latitude hole; (3) Alternate hole; (4) Fixed tripod
legs; (5) Declination pointer; (6) Thumbscrew;
(7) R.A. scale pointer; (8) #1422 low-latitude balance weight.
8. Note the line and arrow extending from the telescope tube in
Fig. 16. This line defines the telescope’s polar axis. Lift the
entire telescope, including tripod, and place the telescope on
a firm and level surface so that this axis is pointing due North
(i.e., if the location of Polaris, the North Star, is known then
point the telescope directly at Polaris).
9. If using the high-latitude tripod leg in the Northern
hemisphere, extend the leg until the telescope’s polar axis
points to Polaris, or due North, an alignment obtained by
sighting along the telescope tube with the telescope oriented
as shown in Fig. 16.
NOTE: Observer’s located in the earth’s Southern Hemisphere
(e.g., South America, Africa, Australia, etc.) should point the
telescope’s polar axis due South.
10.With the telescope now polar-aligned the table tripod should
not be moved, or else polar alignment will be lost. Motions of
the telescope (e.g., to locate and/or track objects) should be
effected only (a) by loosening the locks (6 and 10, Fig. 1),
which permits the optical tube to be moved freely within the
telescope mounting, or (b) more generally, with the locks in
their “locked” positions, by using the arrow keys of the
Electronic Controller.
NOTE: For almost all astronomical observing requirements,
approximate settings of the telescope’s latitude and polar axis are
acceptable. Do not allow undue attention to precise polar
alignment of the telescope to interfere with your enjoyment of the
instrument. In those unusual cases where more precise polar
alignment is desirable, refer to APPENDIX C, page 24.

Fig. 17: Locating Polaris.

Chapterz4: OBSERVING

14
CHAPTER

OBJECTS IN SPACE

Listed below are some of the many astronomical objects that can
be seen with either ETX model telescope.

The Moon
The Moon is, on average, 239,000 miles (380,000km) from Earth.
It is best observed during its crescent or half phase, when
sunlight strikes its surface at an angle, casting shadows and
adding depth to the view (Fig. 18).

Jupiter is the largest planet in our solar system, with a diameter
11 times that of Earth. Jupiter appears as a disk with dark lines
stretching across the surface. These lines are cloud bands in the
atmosphere. Four of Jupiter’s 16 moons (Io, Europa, Ganymede,
and Callisto) can be seen as star-like points of light when you use
even the lowest magnification. The number of moons visible on
any given night changes as they circle around the giant planet.
Saturn is nine times the diameter of Earth and appears as a
small, round disk with rings extending out from either side. In
1610, Galileo, the first person to observe Saturn through a
telescope, did not understand that what he was seeing were
rings. Instead, he believed that Saturn had “ears.” Saturn’s rings
are composed of billions of ice particles, ranging in size from a
speck of dust to the size of a house. The major division in
Saturn's rings, called the Cassini Division, is generally visible
through both ETX models. Titan, the largest of Saturn’s 18 moons
can also be seen as a bright, star-like object near the planet.

Deep-Sky Objects
You can use star charts to locate constellations, individual stars,
and deep-sky objects. Examples of various deep-sky objects are
given below:
Fig. 18: This photo of the Moon shows the rich detail afforded
by shadows.

Stars are large gaseous objects that are illuminated by nuclear
fusion in their core. Because of their vast distances from our solar
system, all stars appear as pinpoints of light, regardless of the
size of the telescope used.

No shadows are seen during a full Moon, causing the overly
bright Moon to appear flat and uninteresting through the
telescope. Using either ETX model, brilliant detail can be
observed on the Moon, including hundreds of lunar craters and
maria, described below.

Nebulae are vast interstellar clouds of gas and dust where stars
are formed. Most impressive of these is the Great Nebula in Orion
(M42), a diffuse nebula that appears as a faint wispy gray cloud.
M42 is 1600 light years from Earth.

Craters are round meteor impact sites covering most of the
Moon’s surface. With no atmosphere on the Moon, no weather
conditions exist, so the only erosive force is meteor strikes. Under
these conditions, lunar craters can last for millions of years.
Maria (plural for mare, seas) are smooth, dark areas scattered
across the lunar surface. These areas are ancient impact basins
that were filled with lava from the interior of the Moon by the depth
and force of the meteor or comet impact.
12 Apollo astronauts left their bootprints on the Moon in the late
1960’s and early 1970’s. However, no telescope on Earth can see
these footprints or any other artifacts. In fact, the smallest lunar
features that may be seen with the largest telescope on Earth are
about one-half mile across.

Open Clusters are loose groupings of young stars, all recently
formed from the same diffuse nebula. The Pleiades (Fig. 19) is an
open cluster 410 light years from Earth. Several hundred stars of
the cluster are visible through both ETX models .
Constellations are large, imaginary patterns of stars believed by
ancient civilizations to be the celestial equivalent of objects,
animals, people, or gods. These patterns are too large to be seen
through a telescope. To learn the constellations, start with an
easy grouping of stars, such as the Big Dipper in Ursa Major.
Then use a star chart to explore across the sky.

NOTE:Except during its early or late crescent phases, the Moon
can be an exceptionally bright object to view through the
telescope. To reduce the brightness and glare, use the #905
Variable Polarizing Filter (see OPTIONAL ACCESSORIES, page18).

Planets
Planets change positions in the sky as they orbit around the Sun.
To locate the planets on a given day or month, consult a monthly
astronomy magazine, such as Sky and Telescope or Astronomy.
Listed below are the best planets for viewing through either ETX
model telescope.
Venus is about nine-tenths the diameter of Earth. As Venus orbits
the Sun, observers can see it go through phases (crescent, half,
and full) much like those of the Moon. The disk of Venus appears
white, as sunlight is reflected off the thick cloud cover that
completely obscures any surface detail.
Mars is about half the diameter of Earth. Through the telescope
it appears as a tiny reddish-orange disk. You may see a hint of
white at one of the planet’s polar ice caps. Approximately every
two years, when Mars is closest to Earth, additional detail and
coloring on the planet's surface may be visible.

Fig. 19: The Pleiades Star Cluster (M45) in the constellation
Taurus.
Galaxies are large assemblies of stars, nebulae, and star
clusters that are bound by gravity. The most common shape is
spiral (such as our own Milky Way), but galaxies can also be
elliptical, or even irregular blobs. The Andromeda Galaxy (M31)
is the closest spiral-type galaxy to our own. This galaxy appears
fuzzy and cigar-shaped. It is 2.2 million light years away in the
constellation Andromeda, located between the large “W” of
Cassiopeia and the great square of Pegasus. Under clear, dark
conditions, M31 can be seen with the naked eye and is a
fascinating object through both ETX models.

z
OBSERVING
PHOTOGRAPHY WITH BOTH ETX MODELS

CHAPTER

Photography through either ETX model requires the addition of the
optional #64 T–Adapter (see OPTIONAL ACCESSORIES, page 17).
With the #64 T-Adapter attached to the telescope (Fig. 20),
through-the-telescope photography is possible with any 35mm
camera body with a removable lens. In this way the telescope
effectively becomes the lens of the camera.

7
Fig.22: Example of a format 2 photo.
To frame an object in the viewfinder of the 35mm camera body,
slightly loosen the knurled attachment ring (3, Fig. 20), which
threads the #64 T-Adapter to the telescope’s photo port; rotate the
camera body to achieve proper framing of the object; then retighten the knurled ring.

3
6

Fig.20: Example of photography through the ETX using the
#64 T–Adapter. (1) Short section of #64 T-Adapter;
(2) Extension section of #64 T-Adapter; (3) Knurled attachment
ring; (4) T-mount; (5) Flip-mirror control in “down” position; (6)
35mm camera body; (7) Format 1.
For through-the-telescope photography, turn the flip-mirror control,
(5, Fig. 20) to the “down” position, allowing light to pass straight
through the telescope and out the photo port (17, Fig. 1). With the
flip-mirror control in the “down” position and the photo port’s dust
cover removed, you can see the front lens of the telescope when
you look through the photo port. The #64 T-Adapter threads onto
the photo port, followed by a T-mount for the particular brand of
35mm camera being used, followed by the camera body (with the
camera lens removed).
The #64 T-Adapter consists of two sections (1 and 2, Fig. 20),
which are threaded together in shipment. You may use either of
the following photographic mounting formats to couple the camera
body to the telescope’s photo port thread.
• Format 1: Camera Body + T-Mount + Section (1) of the #64 TAdapter (7, Fig. 20).
ETX-90EC
1250mm at f/13.8
ETX-125EC
1900mm at f/15
Format 1 utilizes only the short section of the #64 T–Adapter to
permit close-coupling of a camera body to the telescope. In this
format vignetting will occur: the photographic image will appear
on film with a slight darkening at the corners of the 35mm frame
(see Fig. 21).
• Format 2: Camera Body + T-Mount + Sections (1) and (2) of the
#64 T-Adapter (see Fig. 20).

Photography through a long lens, such as the ETX requires
special technique for good results. The photographer should
expect to waste a roll or two of film in acquiring this technique.
Long-lens photography has its own rewards, however, which
short-focus lenses cannot duplicate.
A few tips on photography with both ETX models
1. Use the optional table tripod specific to your model of ETX, or
the #883 Deluxe Field Tripod as a platform for the telescope. At
effective focal lengths of 1250mm to 1450mm (ETX-90EC) or
1900mm to 2310mm (ETX–125EC), even small external
vibrations can easily ruin an otherwise good photo.
CAUTION: With the #64 T-Adapter and a camera body
mounted to the ETX photo port, the telescope can be
rotated vertically only 45°. Moving past this point may
damage the telescope and camera.
2. Use a cable-operated shutter release. Touching the camera
body to operate the shutter will almost certainly introduce
undesirable vibrations.
3. Focus the image with extreme care. While observing the
subject through the camera’s reflex viewfinder, turn the ETX's
focus knob (9, Fig. 1) to achieve the sharpest possible focus.
Note that some 35mm cameras may have an optional focusing
screen (available from the manufacturer) for use with a long
telephoto lens. This screen provides a brighter and clearer
image to focus and is highly recommended.
4. Correct shutter speeds vary widely, depending on lighting
conditions and film used. Trial-and-error is the best way to
determine proper shutter speed in any given application.
NOTE: The camera used with either ETX model may have an
exposure meter that is still active when the standard lens is
removed and the body is connected to the telescope with the
T–mount. If used for terrestrial photography, the camera meter
should be acceptable. If used for astrophotography, the meter
probably will not provide good results since camera meters are not
made to compensate for a dark sky.
5. Terrestrial photography through either ETX model is sensitive
to heat waves rising from the Earth’s surface. Long distance
photography is best accomplished in the early morning hours
before the earth has had time to build up heat.

Fig.21: Example of a format 1 photo.
ETX-90EC
ETX-125EC

1450mm at f/16
2310mm at f/18

Format 2 utilizes both sections of the #64 T-Adapter threaded
together to form a rigid unit. In this configuration there is no field
vignetting: images are illuminated to the edges of a standard
35mm frame (see Fig. 22).

6. Photography of the Moon and planets through either ETX
model can be especially gratifying, but points 1 through 4
should be particularly noted in this case. Lunar or planetary
photography requires that the telescope be polar aligned (see
Polar Alignment Procedure, page 12), and that the
telescope’s motor drive be in operation (see Electronic
Controller Modes, page 11).
NOTE:Long-exposure photography of deep-sky objects is not
practical with either ETX model, since this type of photography
requires special electronic and optical guiding devices not
available for this telescope.

16
CHAPTER

z
Chapter 5: OPTIONAL
ACCESSORIES
A wide assortment of professional Meade accessories is
available for both ETX model telescopes. Meade accessories
greatly extend many important applications of the telescope,
from low-power, wide-field terrestrial viewing to high-power
lunar and planetary observing. The premium quality of these
accessories is well suited to the quality of the instrument itself.

Meade telescopes and accessories, including optional
accessories for ETX telescopes, are available at more than
2000 dealer locations in the U.S. and Canada and through
Meade international distributors worldwide. Once you have
identified the accessories you wish to order, contact your
local Meade authorized dealer.To find a dealer near you, call
(949) 451-1450 or visit the Meade website at
www.meade.com.
#497 Autostar ™ Computer Controller: One of the most
important advances in telescope control in the past 25 years,
the Meade #497 Autostar Computer Controller (Fig. 23) turns
either ETX model into an automatic celestial object locating
system. Just plug Autostar into the telescope’s HBX port in
place of the standardequipment Electronic Controller, do a quick telescope
alignment, and you are ready
to observe any object in the
Autostar’s
14,000-object
database.
Best of all, the Meade
Autostar is easy to use. Even
the most novice observer will
locate dozens of fascinating
objects the very first night out
— from commonly observed
objects, like the rings of
Saturn, the satellites of
Jupiter, and the Orion Nebula
(M42), to more difficult
objects, such as the Ring
Nebula (M57) in Lyra, the
Spiral Galaxy (M33) in
Triangulum, and the Sombrero Galaxy (M104) in Virgo;
to very obscure objects near
the telescope’s threshold of
visibility, such as spiral
galaxy NGC 3310 in Ursa Fig.23: #497 Autostar
Computer Controller.
Major.
Any of Autostar’s database
objects can be called up and entered on the hand controller
display in seconds. The observer then simply presses the
GO TO pushbutton and watches as the telescope automatically
slews to the object and places it in the field of view. Autostar
brings into easy access objects that were previously
unreachable for all but the most dedicated of amateur
astronomers.
Astro Software/Cable Connector Kit:
Meade ETX–90ECand
ETX-125EC Astro
Telescopes equipped with
the Autostar Computer
Controller maybe used in
conjunction with Meade
astro software to operate
the telescope in the GO
TO mode directly from the
display of a personal
computer. With the Meade Fig.24: Astro software.
astro software loaded into
the PC, and with the PC connected to the telescope through
Autostar’s RS-232 serial interface (using the #505 Cable

Connector Set, included with each astro software package),
the observer can point and
click on any object shown on
the PC display. The telescope
then slews to the object at a
speed of 5° per second on
both telescope axes and
places the object in the
telescopic field of view.
Eyepieces: Meade Super
Plössl (SP), Super Wide Angle
(SWA), and Ultra Wide Angle
(UWA) eyepieces in the
standard American-size (1.25”)
barrel diameter (Fig. 25) permit
a wide range of magnifying
powers with both ETX models.
Powers obtained with each
eyepiece are shown in the
following table.

Eyepiece
SP6.4mm
SP9.7mm
SP 12.4mm
SP 15mm
SP 20mm
SP 26mm *
SP 32mm
SP 40mm

Fig. 25: Optional Eyepieces
yield higher and lower
magnifying powers with the
telescope.

ETX-90EC
Power 2X Barlow

ETX-125EC
Power 2X Barlow

195X
129X
101X
83X
63X
48X
39X
31X

390X
258X
202X
166X
126X
96X
78X
62X

297X
196X
153X
127X
95X
73X
59X
48X

594X **
392X
306X
253X
190X
146X
119X
96X

SWA 13.8mm
SWA 18mm
SWA 24.5mm

91X
69X
51X

182X
138X
102X

138X
106X
78X

275X
211X
155X

UWA 4.7mm
UWA 6.7mm

266X
187X

N/A
374X **

404X
284X

N/A
567X **

* Included as standard-equipment with both ETX models.
** Use these eyepieces only under extremely steady
atmospheric conditions.
Meade SP and SWA eyepieces are ideal for general-purpose
astronomical or terrestrial observing. The typical ETX user may
wish to add two or three of these eyepieces to his or her
telescope. An introductory selection might include the SP
9.7mm and SP 15mm eyepieces. The more advanced observer
might select the SP 9.7mm, SP 12.4mm, and SWA 18mm.
Meade SWA eyepieces yield extremely wide fields of view,
perfect for the examination of star fields or diffuse nebulae, or
for terrestrial applications. Under steady viewing conditions,
Meade UWA 4.7mm and
6.7mm eyepieces present the
widest fields of view obtainable
at high powers and are
excellent eyepieces for viewing
the Moon and planets.
#126 2x Barlow Lens: An
amplifying lens, the #126 2x
Barlow Lens (Fig. 26) doubles
the powers of all eyepieces
with which it is used. Insert the
#126 into the telescope’s
eyepiece holder first, followed
by an eyepiece. Example: By
itself the SP 26mm eyepiece
yields a power of 73X with the
ETX-125EC; when used with
the #126 2X Barlow Lens, this
eyepiece yields 146X.

Fig. 26: Use the #126 2x
Barlow Lens to double the
magnification of the eyepiece
employed.

z
OPTIONAL ACCESSORIES
The Meade #126 2x Barlow lens is an achromatic, highperformance, short-focus Barlow Lens, perfectly suited to the
low-profile design of both ETX models. Lens surfaces are multicoated for maximum image contrast and light transmission.
#825 8 x 25mm Right-Angle Viewfinder: Included as standardequipment on ETX-125EC models, the 8 x 25mm Right-Angle
Viewfinder
(Fig.
27)
permits a comfortable 90°
viewing
position with
90mm ETX models as
well. The #825 fits into the
same bracket as the
8x21mm viewfinder supplied with ETX-90EC
telescopes. The finder’s
wide-angle 7.5° actual Fig. 27: #825 Right-Angle
field facilitates object Viewfinder.
location and a helicoid
mechanism allows precise focusing.

#1422 Low-Latitude Balance Weight (for ETX-90EC): If the
ETX-90EC is to be used with the #880 Table Tripod and polaraligned at latitudes below 30°, the telescope can become
unbalanced, particularly if heavier accessories (e.g., a camera
body) are attached to the eyepiece-end of the telescope. The
low-latitude balance weight (4, Fig. 28) slides onto the standard
tripod leg and enables rock-solid stability of the telescope even
at lower latitudes.
NOTE:The low-latitude balance weight for the ETX-125EC is
supplied with the #881 Table Tripod and is recommended for use
at all latitudes covered by the standard tripod leg.
#883 Deluxe Field Tripod: Manufactured of strong, lightweight
extruded aluminum, the #883 Deluxe Field Tripod (Fig. 29)
allows standing or seated observations through both ETX
models. Tripod height is continuously adjustable from 34” to 54”.
Micrometric controls in both azimuth and elevation-angle permit
precise polar alignment of the telescope’s fork mount for
astronomical applications (inset, Fig. 29).

#64 T-Adapter: The basic means of photography through any
ETX telescope, the #64 T-Adapter (1,Fig. 28) threads to the rear
cell of the telescope, followed by a T-Mount appropriate to the
user’s brand of 35mm camera. In this way, the camera body is
rigidly coupled to the telescope's optical system, which in effect
becomes the camera's lens (see PHOTOGRAPHYWITHBOTH ETX
MODELS, page 15).
#880 and #881 Table Tripods: ETX-90EC and ETX-125EC
models permit pushbutton tracking of astronomical objects from
their standard-equipment Electronic Controllers. For fully
automatic tracking a table tripod (Fig. 28), or the #883 Deluxe
Field Tripod may be added allowing for polar alignment of the
telescope.

1
2
3
Fig.28: Example of astronomical photography using the
#880 Table Tripod with an ETX-90EC. (1) #64 T-Adapter;
(2) Standard tripod leg; (3) Fixed tripod legs;
(4) Balance weight; (5) High-latitude tripod leg.
Each table tripod includes two fixed legs and two variable-length
legs inscribed with a range of latitude settings for quick polar
alignment. The #880 Table Tripod (for the ETX–90EC) and #881
Table Tripod (for the ETX-125EC) attach quickly to the telescope
drive base.
Two identical fixed tripod legs (3, Fig. 28) mount to holes on the
side of the drive base. The adjustable standard tripod leg (2, Fig.
28), with its two latitude scales, is mounted to one of two holes
on the bottom of the drive base. It permits the telescope to be
polar aligned for latitudes between 22° and 48.5° (ETX-90EC) or
between 23.25° and 49.5° (ETX-125EC). The shorter highlatitude tripod leg (5, Fig. 28) is substituted for the standard
tripod leg at latitudes between 44° and 66° (ETX-90EC) or 44.5°
and 67° (ETX-125EC).

Fig. 29: The #883 Deluxe Field Tripod shown with an ETX90EC Astro Telescope, set up in the Alt/Az configuration
(tripod head locked at 90°), for terrestrial applications. (Inset)
Tripod head tilted for polar alignment.
Designed exclusively for both ETX model telescopes, the #883
Deluxe Field Tripod includes all the rigidity and stability required
for high-power observing through the telescope. For terrestrial
observing, where altazimuth orientation of the telescope is
desirable, the tripod head tilts and locks at 90°.
#932 45° Erecting Prism: All ETXmodels include an internal
optically-flat mirror to reflect light to the telescope’s 90°
astronomical observing position. In this position the telescope’s
image is upright, but reversed. For terrestrial observing with
either ETX model, the #932 45° Erecting Prism (1, Fig. 30) gives
a fully correctly oriented image and a convenient 45° observing
angle. The #932 prism threads onto the telescope’s photo port
(17, Fig. 1). An eyepiece of any focal length (magnifying power)
may be inserted into the #932 prism. Note that the flip-mirror
control (4, Fig. 30) must be in the “down” position for use with
the #932 prism.

17
CHAPTER

z ACCESSORIES
OPTIONAL

18
CHAPTER

#1244 and #1247 Electric
Focusers:

Fig.30: The #932 45° Erecting Prism shown threaded to the
rear cell of an ETX-90EC. (1) #932 45° Erecting Prism;
(2) Eyepiece; (3) Knurled lock-ring; (4) Flip-mirror control.
Important Note: In the most discriminating applications, such
as long-distance observing of delicate bird feather-structure,
both ETX models’ internal, optically-flat mirror yields a higherresolution image than is possible with any prism, including the
#932. In these special cases users of both ETX models are
advised to observe with the eyepiece in the standard 90°
eyepiece holder (as shown in Fig.1), with the flip-mirror control
in the “up” position. This admonition applies only to situations
requiring extraordinarily high optical resolution and where the
observer’s eye is well trained to observe very fine detail. In
typical terrestrial applications, no image differences between
the two eyepiece locations can generally be noted.
#765 Soft Carry Bag: The Meade soft-padded carry bag (Fig.
31) is well suited to travel with the ETX-90EC. Each carry bag
includes a shoulder strap and permits ready transport of the
complete telescope, including accessories.

Meade-engineered
for
smooth, rapid focusing with
both ETX models, each
electric focuser (Fig. 33)
includes coarse and microfine speeds. The standardequipment hand controller
accepts one (user-supplied)
9-volt battery. On both ETX
models, the focuser plugs
into, and is powered by, the
telescope’s control panel,
with operation effected
through either the Electronic
Controller or the optional
#497 Autostar Computer
Controller: the #1244 for
ETX-90EC and the #1247
for ETX-125EC.

Fig.33: #1244 Electric
Focuser.
Hard Carrying Cases: For secure portability of the ETX-90EC
(#774 Hard Case) or ETX-125EC (#775 Hard Case) in the field,
Meade hard carrying cases (Fig. 34) are fully lined with fitted
foam inserts. They accept the complete telescope and
accessories (e.g., additional eyepieces, table tripod, the
Electronic Controller, Autostar, and much more).

Fig.31: The #765 Soft Carry Bag for the ETX-90EC.
Power Adapters and Cords: In addition to their internal battery
packs, ETX-90ECand ETX-125EC telescopes may be powered
from standard 115vAC home electricity with the #541 AC
Adapter. The #541 plugs into any standard home outlet and
includes a 25 ft. cord connecting to the telescope’s control
panel. Input voltage to the telescope is 12vDC. Alternately,
either telescope may be powered in the field from an automobile
cigarette lighter plug by using the #607 Power Cord (Fig. 32), a
25-ft. cord that plugs into the telescope’s control panel and
supplies 12vDC directly from the car battery.

Fig.32: #607 Power Cord.

Fig.34: #775 Hard Carrying Case shown with an
ETX-90EC.
#905 Variable Polarizing Filter:
For glare reduction in observing
the Moon, the #905 Variable
Polarizer (Fig. 35) includes two
polarizer filters, mounted in a
specially machined cell. The
#905 filter permits variable
settings of light transmission,
between 5% and 25%, to
account for varying lunar-surface
brightness according to the Fig.35: #905 Variable
phase of the Moon. The #905 Polarizing Filter.
accepts 1.25” barrel-diameter
eyepieces of any focal length.

z AND SERVICING
Chapter 6: MAINTENANCE
General Maintenance
Both ETX model telescopes are precision optical instruments
designed to yield a lifetime of rewarding applications. Given the
care and respect due any precision instrument, the telescopes
will rarely require factory servicing or maintenance. Use the
following guidelines:
1. Avoid cleaning the telescope’s optics: a little dust on the
front surface of the telescope’s correcting lens causes
virtually no degradation of image quality and should not be
considered reason to clean the lens.
2. When absolutely necessary, remove dust from the front lens
with gentle strokes of a camel-hair brush or blow it off with
an ear syringe (available at any pharmacy). Do not use a
commercial photographic lens cleaner.
3. You may remove organic materials (e.g., fingerprints) from
the front lens with a solution of 3 parts distilled water to
1 part isopropyl alcohol. A single drop of biodegradable
dishwashing soap may be added per pint of solution. Use
soft, white facial tissues and make short, gentle strokes.
Change tissues often.
CAUTION: Do not use scented, colored, or lotioned
tissues or damage could result to the optics.
4. In the very rare situation where cleaning the inside surface
of the corrector lens becomes necessary, unthread the lens
cell located at the front of the main tube. The entire
correcting lens and secondary mirror system are mounted in
this cell. You may use the lens-cleaner solution described in
step 3 to clean the inside surface of the lens.
CAUTION: Do not touch the aluminized circular
surface of the secondary mirror with a finger, a tissue,
or any other object.This will almost certainly scratch
the mirror surface.
NOTE:When cleaning the inside surface of the correcting lens,
leave the lens mounted in its metal cell throughout the process.
Do not remove the lens from its metal housing or optical
alignment of the lens will be lost, necessitating a return of the
telescope to the Meade factor y.
5. If either ETX model is used outdoors on a humid night,
telescope surfaces may accumulate water condensation.
While such condensation does not normally cause any
damage to the telescope, it is recommended that the entire
telescope be wiped down with a dry cloth before being
packed away. Do not, however, wipe any of the optical
surfaces. Rather, simply allow the telescope to sit for some
time in warm indoor air, so that the wet optical surfaces can
dry unattended. In addition, the dust cap should not be
placed back on to the optical tube until the telescope is
thoroughly dry.
6. If either ETX model is not to be used for an extended period,
perhaps for one month or more, it is advisable to remove the
eight AA-size batteries from inside the drive base. Batteries
left installed for prolonged periods may leak, causing
damage to the telescope’s electronic circuitry (see Assembly
Instructions, page 5).
7. The super-gloss anodized finish of both ETX model’s deepviolet optical tube fades if left in direct sunlight for prolonged
periods.
8. Do not leave either ETX model outdoors on a warm day or
inside a sealed car for an extended period of time;
excessive ambient temperatures can damage the
telescope’s internal lubrication and electronic circuitry.
9. A set of two (English-format) hex wrenches is provided with
both ETX models. These wrenches are used as follows:

• Small wrench (.05”): Use the small wrench to tighten the setscrews of any knobs that may loosen (e.g., the focus knob
or flip-mirror control knob).
• Medium wrench (1/16”): This wrench is used to detach the
viewfinder bracket from the telescope’s rear cell.

Storage and Transport
When the telescope is not in use, store it in a cool, dry place.
Do not expose the instrument to excessive heat or moisture. It
is best to store the telescope in its original box with the vertical
and horizontal locks (6 and 10, Fig. 1) in the unlocked positions.
If shipping the telescope, use the original box and packing
material to protect the telescope during shipment.
When transporting the telescope, take care not to bump or drop
the instrument; this type of abuse can damage the optical tube
and/or the objective lens. It is highly recommended to use an
optional carry case to transport the telescope (see OPTIONAL
ACCESSORIES, page 18).

Inspecting the Optics
A Note About the “Flashlight Test: If a flashlight or other highintensity light source is pointed down the main telescope tube,
the view (depending upon the observer’s line of sight and the
angle of the light) may reveal what appear to be scratches, dark
or bright spots, or uneven coatings, giving the appearance of
poor quality optics. These effects are only seen when a high
intensity light is transmitted through lenses or reflected off the
mirrors, and can be seen on any high-quality optical system,
including giant research telescopes.
The optical quality of a telescope cannot be judged by the
“flashlight” test; the true test of optical quality can only be
conducted through careful star testing.

Troubleshooting
The following suggestions may be helpful with operation of the
ETX-90EC and ETX-125EC.

The power indicator light on the telescope does
not come on or there is no response when
pressing the Electronic Controller arrow keys:
• Verify that the computer control panel power switch (1, Fig.
5) is in the ON position.
• Verify that the Electronic Controller cord (4, Fig. 6) is firmly
connected to the HBX port (3, Fig. 5).
• If using internal power (batteries), verify that the batteries are
installed correctly and that they have sufficient charge (see
Assembly Instructions, page 5).
NOTE: If the batteries are getting low on charge, there will be
a marked difference in the slew speed. The speed indicator
lights may also flash and the speed may change. If any of these
symptoms occurs, turn the power off and replace the batteries.
• If using an external power source, verify that it is properly
connected between the 12-volt connector (4, Fig. 5) and
either a wall plug (AC source) or a car cigarette lighter (DC
source).
• If the Electronic Controller does not respond to commands,
move the power switch to OFF and then back to ON.
• If the telescope does not slew after power is applied or if the
motor quits or stalls, verify that there are no physical
obstructions that would impede telescope movement.
• If all physical obstacles are removed and the telescope still
does not move properly, turn off the power and unplug the
Electronic Controller. Plug the Electronic Controller back in
and turn the power back on.

19
CHAPTER

CHAPTER

z
MAINTENANCE
AND SERVICING
Unable to see an image through the eyepiece:
• Confirm that the lens cover has been removed from the
telescope.
• Confirm that the flip-mirror control (16, Fig. 1) is in the “up”
position if using the eyepiece holder (4, Fig. 1) so that light
is directed to the eyepiece (1, Fig. 1). Confirm that the flipmirror control is in the “down” position if using the #932
Erecting Prism or doing photography with either ETX model
(see Telescope Controls, page 6 and PHOTOGRAPHY WITH
BOTH ETX MODELS, page 15).

Object appears in the viewfinder but not in the
eyepiece:
• The viewfinder is not properly aligned with the telescope
(see THEVIEWFINDER page 8).

Slew speed does not change when you press the
SPEED key, or the telescope moves slowly even
though the fast slew speed is chosen:
• Verify that only one light is illuminated on the Electronic
Controller. If more than one light is on or blinking, the Mode
function is active. Exit the Mode function by pressing and
holding the MODE key until only one light is on (see
Electronic Controller Modes, page 11).
• The battery power may be low (see Assembly Instructions,
page 5).

optimal viewing, use the telescope outside in the open air
instead of observing through an open or closed window or
screen.
• If viewing a land object on a warm day, heat waves will distort
the image (see Terrestrial Observing, page 10).
• For clear viewing of objects, turn the focus knob (9, Fig. 1)
slowly since the “in-focus” point of a telescope is precise.
Turning the focus knob too quickly may cause the focus point
to pass without notice.
• The optics within the telescope need time to adjust to the
outside ambient temperature to provide the sharpest image.
To cool down the optics, set the telescope outside for 10 to
15 minutes before observing begins.

Telescope moves off a terrestrial object while
observing:
• The motor drive may be activated (see Modes of Operation,
page 11).
• Verify that the vertical and horizontal locks are tight (see
Telescope Controls, page 6).

Telescope does not move past a certain point:
• The built-in vertical or horizontal rotational “stops” may have
been reached (see Rotational Limits, page 6).

Telescope pauses when changing slew direction:

Telescope does not track a celestial object:

• This pause is normal (see Arrow Keys, page 6).

• The telescope tracks celestial objects automatically only if it
is placed in the polar mode (see Modes of Operation, page
11) and the telescope is polar aligned (see Polar Alignment,
page 12) using the #880 (ETX-90EC), #881 (ETX-125EC)
Table Tripod, or #883 Deluxe Field Tripod (see OPTIONAL
ACCESSORIES, page 17). The more accurate the polar
alignment, the longer the telescope’s motor drive holds an
object in the field of view of the eyepiece. If using the Alt/Az
mode, track celestial objects by using the directional arrows
on the Electronic Controller. Automatic racking of objects in
the Alt/Az mode requires the optional #497 Autostar
Computer Controller.

A terrestrial object appears reversed left-for-right:

Images through the eyepiece appear unfocused or
distorted:
• The magnification may be too high for the viewing conditions. Back off to a lower power eyepiece (see Understanding Magnification, page 9).
• If inside a warm house or building, move outside. Interior air
conditions may distort terrestrial or celestial images, making
it difficult, if not impossible, to obtain a sharp focus. For

• An eyepiece in the standard 90° observing position (4, Fig.
1) reverses an object left-for-right:. To view a correctly
oriented image requires the optional #932 Erecting Prism
(see OPTIONALACCESSORIES, page 17).

Meade Customer Service
If you have a question concerning either ETX model, call the
Meade Instruments Customer Service Department at
(949) 451-1450, or fax at (949) 451-1460. Customer Service
hours are 8:30 AM to 4:30 PM, Pacific Time, Monday through
Friday. In the unlikely event that the ETX requires factory
servicing or repairs, write or call the Meade Customer Service
Department first, before returning the telescope to the factory,
giving full particulars as to the nature of the problem, as well
as your name, address, and daytime telephone number. The
great majority of servicing issues can be resolved by
telephone, avoiding return of the telescope to the factory.

z
TELESCOPE SPECIFICATIONS

Specifications: ETX-90EC Astro Telescope

Specifications: ETX-125EC Astro Telescope

Optical design . . . . . . . . . . . . . . . . . . . Maksutov-Cassegrain
Primary mirror diameter . . . . . . . . . . . . . . . . . . 96mm (3.78”)
Clear aperture . . . . . . . . . . . . . . . . . . . . . . . . . . 90mm (3.5”)
Focal length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1250mm
Focal ratio (photographic speed). . . . . . . . . . . . . . . . . . f/13.8
Near focus (approx) . . . . . . . . . . . . . . . . . . . . . 11.5 ft (3.5m)
Resolving power. . . . . . . . . . . . . . . . . . . . . . . . . 1.3 arc secs
Super multi-coatings (EMC). . . . . . . . . . . . . . . . . . . standard
Limiting visual stellar magnitude (approx.). . . . . . . . . . . . 11.7
Image scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.16°/inch
Maximum practical visual power . . . . . . . . . . . . . . . . . . 325X
Optical tube dimensions
(dia. x length) . . . . . . . . . . 10.4cm x 27.9cm (4.1” x 11”)
Eyepiece. . . . . . . . . . . . . . . . . . . . . . . . . Super Plössl 26mm
Viewfinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 x 21mm
Secondary mirror obstruction (dia.; %) . . 27.9mm (1.1”); 9.6%
Telescope mounting . . . . . . . . . . . . . . . fork type; double tine
Setting circle diameters . . . . . . . . . . . . . . . . Dec: 3.5”; RA: 7”
Input voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 volts DC

Optical design . . . . . . . . . . . . . . . . . . . Maksutov-Cassegrain
Primary mirror diameter . . . . . . . . . . . . . . . . . 138mm (5.43”)
Clear aperture . . . . . . . . . . . . . . . . . . . . . . . . . 127mm (5.0”)
Focal length . . . . . . . . . . . . . . . . . . . . . . . . . 1900mm (74.8”)
Focal ratio (photographic speed) . . . . . . . . . . . . . . . . . . . f/15
Near focus (approx). . . . . . . . . . . . . . . . . . . . . . . 5.5m (18 ft)
Resolving power. . . . . . . . . . . . . . . . . . . . . . . . . 0.9 arc secs
Super multi-coatings (EMC). . . . . . . . . . . . . . . . . . . standard
Limiting visual stellar magnitude (approx.). . . . . . . . . . . . 12.5
Image scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.76°/inch
Maximum practical visual power . . . . . . . . . . . . . . . . . . 500X
Optical tube dimensions
(dia. x length) . . . . . . . . . 14.6cm x 36cm (5.75” x 14.2”)
Eyepiece. . . . . . . . . . . . . . . . . . . . . . . . . Super Plössl 26mm
Viewfinder. . . . . . . . . . . . . . . . . . . . . . . 8 x 25mm right-angle
Secondary mirror obstruction (dia.; %). . 39.4mm (1.6”); 9.6%
Telescope mounting . . . . . . . . . . . . . . . fork type; double tine
Setting circle diameters. . . . . . . . . . . . . . . . Dec: 4.3”; RA: 9”
Input voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 volts DC
Motor Drive System . . DCservo motors with encoders, both axes
Slow-Motion Controls . . . . . . . . . electric, 4 speed, both axes
Optional Autostar Capability. . . . . . . . . . . . . . . . . . . . . . . yes
Hemispheres of operation . . . . . North and South, switchable
Bearings:
Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acetal
Azimuth . . . . . . . . . . . . . . . . . . . . . . . radial ball bearing
Materials:
Tube body . . . . . . . . . . . . . . . . . . . . . . . . . . . aluminum
Mounting . . . . . . . . . . high-impact ABS, zinc-reinforced
Primary mirror . . . . . . . . . . . . . . . . . . . . . . Pyrex® glass
Correcting lens. . . . . . . . . . . BK7 optical glass, Grade-A

Motor DriveSystem DCservo motors with encoders, both axes
Slow-Motion Controls . . . . . . . . . electric, 4 speed, both axes
Optional Autostar Capability. . . . . . . . . . . . . . . . . . . . . . . yes
Hemispheres of operation . . . . . North and South, switchable
Bearings:
Altitude. . . . . . . . . . . . . . . . . . . . . . UHMW polyethylene
Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PTFE
Materials:
Tube body . . . . . . . . . . . . . . . . . . . . . . . . . . . aluminum
Mounting . . . . . . high-impact ABS, aluminum-reinforced
Primary mirror . . . . . . . . . . . . . . . . . . . . . . Pyrex® glass
Correcting lens. . . . . . . . . . . BK7 optical glass, Grade-A
Telescope dimensions:
. . . . . . . . . . . . . . . . 38cm x 18cm x 22cm (15” x 7” x 9”)
Telescope net weight:
(incl. Electronic Controller & batteries) . . 3.5kg (7.8 lbs)
Telescope shipping weight. . . . . . . . . . . . . . . 5.8kg (12.8 lbs)
Battery Life (approx.):
with Electronic Controller . . . . . . . . . . . . . . . . . . . 45 hrs
with Autostar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 hrs

Telescope dimensions:
. . . . . . . . . . 48cm x 23cm x 27cm (19” x 8.9” x 10.8”)
Telescope net weight:
(incl. Electronic Controller & batteries) . . 7.9kg (17.4 lbs)
Telescope shipping weight. . . . . . . . . . . . . . 12.4kg (27.4 lbs)
Battery Life (approx.):
with Electronic Controller . . . . . . . . . . . . . . . . . . . 45 hrs
with Autostar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 hrs

CHAPTER

z
Appendix A:TRACKING
MOTOR SPEED

APPENDIX

In the polar mode the Electronic Controller normally tracks
objects at the sidereal rate (see Sidereal Rate, page 10). For
most observing sessions (once the telescope has been polar
aligned and the tracking motor activated), there is little need to
change this speed.
For objects, like the Moon or a comet, that move at slightly
different rates, the Electronic Controller arrow keys (1, Fig. 6)
are sufficient to move the telescope slightly as the object very
slowly moves off-center through the eyepiece field.

Indicator Light Key
The procedures in this
manual identify the status of
the four indicator lights in a
box to the left of the
appropriate step. They are
depicted as on, blinking or
off, depending on the mode
at that point.

Light No.

Light Status

Light 1

Light 2

Blinking

Light 3

Off

Light 4

To change the tracking rate, for extended observations of an
object not moving at the sidereal rate, follow the procedure for
the appropriate hemisphere:
Northern Hemisphere Polar:

Southern Hemisphere Polar:

Press and hold the MODE key (5, Fig. 6) until the Mode
function is active (i.e., lights 1 and 2 are on steady; lights
3 and 4 signify whatever tracking mode was last chosen).

Press and hold the MODE key (5, Fig. 6) until the Mode
function is active (i.e., lights 1 and 2 are on steady; lights
3 and 4 signify the tracking mode last chosen).

Press the SPEED key (3, Fig. 6) until lights 1, 2,
and 3 are on steady with light 4 blinking. The
telescope is now in the Northern Hemisphere Polar
mode.

Press the SPEED key (3, Fig. 6) until lights 1 and
2 are on steady, light 3 is off, and Light 4 is
blinking.

Press the INkey and light 4 comes on steady. The
tracking rate is now 0.5% faster than sidereal.
Continue pressing IN until the desired speed is
reached.

Press the INkey and light 4 comes on steady. The
tracking rate is now 0.5% faster than sidereal.
Continue pressing INuntil the desired speed is
reached.

NOTE:The tracking rate can be increased by up to 65%
(127 presses of the IN key).

To use a rate slower than sidereal, press the OUT
key until light 4 blinks again (sidereal rate). Press
the OUT key again and light 4 goes out, signifying
a tracking rate 0.5% slower than sidereal. Pressing
an additional 3 to 4 times will slow the tracking rate
to the lunar rate.

NOTE:The tracking rate can be decreased by up to 65%
(127 presses of the OUT key).

Press and hold the MODE key until only a single
light is on. This exits the Mode function. If Northern
or Southern Hemisphere polar mode was chosen,
the motor drive starts operating at the sidereal rate.
Use the four arrow keys (1, Fig. 6) to slew the
telescope to the desired object. To change the slew
speed, press the SPEED key.

z CHARTS
Appendix B: HELPFUL

Latitude Chart for Major Cities of the World

Star Locator

To aid in the polar alignment procedure (see page 12), latitudes
of major cities around the world are listed below. To determine
the latitude of an observing site not listed on the chart, locate
the city closest to your site. Then follow the procedure below:

Following is a list of bright stars with their R.A. and Dec.
coordinates, along with the Northern hemisphere season when
these stars are prominent in the night sky. This list will aid the
observer to find alignment stars at various times of the year.
For example, if it is a midsummer evening in the Northern
hemisphere, Deneb in the constellation Cygnus, would be an
excellent alignment star, while Betelgeuse could not be used
because it is in the winter constellation Orion and thus below
the horizon.

Northern hemisphere observers (N): If the site is over 70
miles (110 km) north of the listed city, add one degree for every
70 miles. If the site is over 70 miles south of the listed city,
subtract one degree per 70 miles.
Southern Hemisphere observers (S): If the site is over 70
miles north of the listed city, subtract one degree for every 70
miles. If the site is over 70 miles south of the listed city, add one
degree per 70 miles.
UNITED STATES

City

State

Latitude

Albuquerque
Anchorage
Atlanta
Boston
Chicago
Cleveland
Dallas
Denver
Detroit
Honolulu
Jackson
Kansas City
Las Vegas
Little Rock
Los Angeles
Miami
Milwaukee
Nashville
New Orleans
New York
Oklahoma City
Philadelphia
Phoenix
Portland
Richmond
Salt Lake City
San Antonio
San Diego
San Francisco
Seattle
Washington
Wichita

New Mexico
Alaska
Georgia
Massachusetts
Illinois
Ohio
Texas
Colorado
Michigan
Hawaii
Mississippi
Missouri
Nevada
Arkansas
California
Florida
Wisconsin
Tennessee
Louisiana
New York
Oklahoma
Pennsylvania
Arizona
Oregon
Virginia
Utah
Texas
California
California
Washington
District of Columbia
Kansas

35° N
61° N
34° N
42° N
42° N
41° N
33° N
40° N
42° N
21° N
32° N
39° N
36° N
35° N
34° N
26° N
46° N
36° N
30° N
41° N
35° N
40° N
33° N
46° N
37° N
41° N
29° N
33° N
38° N
47° N
39° N
38° N

EUROPE

City

Country

Latitude

Amsterdam
Athens
Bern
Copenhagen
Dublin
Frankfurt
Glasgow
Helsinki
Lisbon
London
Madrid
Oslo
Paris
Rome
Stockholm
Vienna
Warsaw

Netherlands
Greece
Switzerland
Denmark
Ireland
Germany
Scotland
Finland
Portugal
England
Spain
Norway
France
Italy
Sweden
Austria
Poland

52° N
38° N
47° N
56° N
53° N
50° N
56° N
60° N
39° N
51° N
40° N
60° N
49° N
42° N
59° N
48° N
52° N

APPENDIX

Season

Star Name

Constellation

R.A.

Spring
Spring
Spring

Arcturus
Regulus
Spica

Bootes
Leo
Virgo

14h16m 19° 11"
10h09m 11° 58"
13h25m -11° 10"

Summer
Summer
Summer
Summer

Vega
Deneb
Altair
Antares

Lyra
Cygnus
Aquilla
Scorpius

18h37m
20h41m
19h51m
16h30m

Fall
Fall
Fall

Markab
Fomalhaut
Mira

Pegasus
23h05m 15° 12"
Pisces Austrinis 22h58m -29° 38"
Cetus
02h19m -02° 58"

Winter
Winter
Winter
Winter

Rigel
Orion
Betelgeuse Orion
Sirius
Canis Major
Aldebaran Taurus

05h15m
05h55m
06h45m
04h35m

Dec.

38° 47"
45° 17"
08° 52"
-26° 26"

-08° 12"
07° 25"
-16° 43"
16° 31"

SOUTH AMERICA

City

Country

Latitude

Asuncion
Brasilia
Buenos Aires
Montevideo
Santiago

Paraguay
Brazil
Argentina
Uruguay
Chili

25° S
24° S
35° S
35° S
34° S

ASIA

City

Country

Latitude

Beijing
Seoul
Taipei
Tokyo
Victoria

China
South Korea
Taiwan
Japan
Hong Kong

40° N
37° N
25° N
36° N
23° N

City

Country

Latitude

Cairo
Cape Town
Rabat
Tunis
Windhoek

Egypt
South Africa
Morocco
Tunisia
Namibia

30° N
34° S
34° N
37° N
23° S

City

State

Latitude

Adelaide
Brisbane
Canberra
Alice Springs
Hobart
Perth
Sydney
Melbourne

South Australia
Queensland
New South Wales
Northern Territory
Tasmania
Western Australia
New South Wales
Victoria

35° S
27° S
35° S
24° S
43° S
32° S
34° S
38° S

AFRICA

AUSTRALIA

24
APPENDIX

z ALIGNMENT; SETTING CIRCLES
Appendix C: PRECISE POLAR
Precise Polar Alignment
Important note: For almost all astronomical observing
requirements, approximate settings of the telescope’s latitude
and polar axis are acceptable. Do not allow undue attention to
precise polar alignment of the telescope to interfere with your
enjoyment of the instrument.
If desired, you may obtain more precise polar alignment by first
accomplishing basic polar alignment as detailed in Polar
Alignment Procedure, page 12, then returning to this procedure:

NOTE: The R.A. circle has two rows of numbers from 0 to 23,
corresponding to the hours of a 24-hour clock.The upper row of
numbers is used by observers in the Earth’s Northern
hemisphere, the lower row by observers in the Earth’s Souther n
Hemisphere.
• Declination Setting Circle: The Dec. setting circle (Fig. 37)
has been factory set to read the correct Declination of sky
objects.

NOTE:This procedure moves the telescope physically to line up
precisely with the celestial pole. Do not use the Electronic
Controller arrow keys to move the telescope electronically or
polar alignment will be lost.
1. Orient the entire telescope, including tripod or tripod legs, so
that the polar axis is pointing toward Polaris (Fig. 16).
2. While observing through the SP 26mm eyepiece of the
telescope, adjust the length of the adjustable tripod leg until
Polaris is visible in the eyepiece. Use a combination of (a)
lifting and turning the entire telescope (or nudging the position
of one of the fixed tripod legs) and (b) adjusting the length of
the adjustable tripod leg to place Polaris in the center of the
telescope's field.
3. Repeat step 2 of this procedure in about 15 minutes to see
how much drift has taken place and to make the alignment
more precise.
Although the above procedure is somewhat tedious (since the
field of view of the telescope with the SP26mm eyepiece is only
about 1°), it is a worthwhile effort if precise polar alignment is
desired (e.g., if photography of the Moon or a planet is to be
performed). With Polaris placed in the center of the telescope’s
eyepiece, the telescope is now polar aligned within about one or
two degrees, a level of alignment precision more than sufficient
for almost any observing application.
To provide the most stable platform from which to polar align both
ETX models, it is recommended to purchase the #883 Deluxe
Field Tripod. The tripod head tilts easily to the local latitude angle
for quick polar alignment, and it locks in a 90° position to facilitate
Alt/Az viewing (see OPTIONALACCESSORIES, page 17).

Setting Circles
Both ETX models are equipped with R.A. and Dec setting circles
(14 and 18, Fig. 1) to aid in locating faint celestial objects when
the telescope has been polar aligned. Setting circles emulate the
celestial coordinates found on star charts or in sky catalogs. Any
charted object is easily located by coordinates in R.A. (in hours,
minutes, and seconds, from 0h 0m 0s to 23h 59m 59s) and Dec.
(in degrees from 0° to ±90°).
With either ETX model polar aligned, use the Electronic
Controller arrow keys (1, Fig. 6) to move the telescope in R.A.
(left and right keys) and Dec. (up and down keys).
NOTE:The Dec setting circle is located on the left arm of the
telescope fork mount. The right arm of the mount contains a
graduated circle (mounted behind the knurled knob of the
vertical lock), without Dec. numbers.
• Right Ascension Setting Circle: Since celestial objects move
in R.A., the R.A. setting circle (Fig. 36) must be reset as each
object is located during an observing session. The R.A. pointer
is located on the drive base 90° counterclockwise from the
telescope’s computer control panel (11, Fig. 1) immediately
under the R.A. circle.

Fig.36: Section of Right Ascension setting circle.

Fig.37: Section of Declination setting circle.
Because the smooth knob on this fork mount arm need never
be loosened, the Dec setting circle should always remain
calibrated. If for some reason this knob becomes loose and
the Dec. setting circle must be recalibrated, level the optical
tube (5, Fig. 1) so that it is parallel to the drive base. Loosen
the smooth knob covering the Dec. setting circle until the
setting circle moves freely. Reposition the setting circle so that
the 0 setting aligns with the Dec. pointer (5,Fig.16). Retighten
the Dec. knob.
To use the setting circles to find astronomical objects, the ETX
must first be polar aligned. It is advisable that the motor drive be
turned on (see Modes of Operation, page 11) and that a lowpower eyepiece (e.g., the SP 26mm eyepiece) be employed.
Then use the following procedure:
1. Identify the celestial coordinates (R.A. and Dec) of a bright,
easy-to-find object, such as a bright star. (Avoid using Polaris
or any object near Polaris.) Coordinates of some bright stars
are listed in the Star Locator (page 23), or use a star chart.
Center this object in the telescope’s field of view.
2. Manually turn the R.A. circle (14, Fig. 1) to read the R.A. of the
object at the R.A. pointer (7, Fig. 16).
3. The R.A. circle is now calibrated to read the correct R.A. of
any object at which the telescope is pointed. The Dec. circle is
already calibrated through polar alignment.
4. To find another object, again identify the R.A. and Dec.
coordinates. Then, without touching the setting circles, move
the telescope (manually, by unlocking the vertical and
horizontal locks, or by slewing the telescope using the
Electronic Controller arrow keys) so that the R.A. and Dec.
pointers read the coordinates of the second object.
5. If the above procedure has been followed carefully, the
second object will now be in the telescope’s field of view.
NOTE:Since the second object (i.e., the object to be located) is
in constant motion, once the R.A. circle is calibrated (step 2,
above) the telescope should be moved rapidly to read the
coordinates of the second object. Otherwise the second object
will no longer be in the position indicated by the R.A.circle.
Using setting circles requires a developed technique. When
using the circles for the first time, try hopping from one bright star
(the calibration star) to another bright star of known coordinates.
Practice moving the telescope from one easy-to-find object to
another. In this way the precision required for accurate object
location becomes familiar.

Appendix D: ROADMAPz TO THE STARS
The night sky is filled with wonder and intrigue. You too can
enjoy exploring the universe simply by following a few pointers
on a roadmap to the stars.
First, find the Big Dipper, which is part of the constellation Ursa
Major. (It is in the center of Fig. 38.) The Big Dipper is usually
easy to locate year round in North America due to its proximity
to the North Star, Polaris.
Extending directly out from the far side of the Big Dipper’s cup
is the constellation Orion. One of the most exquisite areas of
the winter sky, Orion is distinguished by two bright stars, Rigel
and Betelgeuse, and Orion’s belt, which is marked by three
stars in a row. The Orion Nebula is located south of the belt
and is one of the deep-sky objects most observed by amateur
astronomers.
Extending from the pointer stars (end stars) of the Big Dipper’s
cup is Polaris, the closest star to the northernmost point of the
celestial sphere. Extending from Polaris is the Great Square
shared by the constellation Pegasus and Andromeda. Within

Andromeda is the Andromeda Galaxy, the closest large galaxy
to our solar system at about 2.2 million light-years away.
The Summer Triangle is a notable region in the sky to the left
of the handle of the Big Dipper. The triangle is made up of three
very bright stars: Vega, Deneb, and Altair.
By drawing an imaginary line outward from the handle of the
Big Dipper you reach the southern constellation Scorpius.
Scorpius curves to the left like the tail of a scorpion in the sky,
or like letter “J.”
Amateur astronomers commonly use the phrase “Arc to
Arcturus and spike to Spica” to refer to the area directly off
the arc in the handle of the Big Dipper. Follow the arc to
Arcturus, the second brightest star in the Northern Hemisphere,
then spike down to Spica, the 16th brightest star in the sky.
Now follow the arc in the handle of the Big Dipper in the
opposite direction and you reach another famous arc called
The Sickle, in the constellation Leo.

Fig. 38: Road Map to the Stars.

25
APPENDIX

z AND THE UNIVERSE
Appendix E: YOU

26
APPENDIX

E
The distance from the Earth to the Moon
Radius = 239,000 miles

The distances between the planets
The distance from the Earth to the Sun is 93 million miles or 1 Astronomical Unit (AU)

Pluto’s elliptical orbitis eccentric and carriesthe planet
inside theorbit ofNeptune at itsclosest approachto theSun.

The distance between stars
The distance from the Sun to the nearest star is about 4.3 light-years, or 25 trillion miles. This distance is so large that if a scale
model were created with the Earth one inch away from the Sun, the nearest star would have to be placed over 4 miles away!

Approximately one hundred billion stars, including the Sun, comprise the Milky Way Galaxy, which is a spiral-shaped
collection of stars believed to be more than 100,000 light years in diameter.

The distances between galaxies
Milky Way Galaxy

Andromeda Galaxy (M31)

Whirlpool Galaxy (M51)

The Sun

2.2 million light-years

35 million light-years

MEADE LIMITED WARRANTY
Every Meade telescope, spotting scope, and telescope accessory is warranted by Meade Instruments Corporation (“Meade”)
to be free of defects in materials and workmanship for a period of ONE YEAR from the date of original purchase in the U.S.A.
and Canada. Meade will repair or replace a product, or part thereof, found by Meade to be defective, provided the defective
part is returned to Meade, freight-prepaid, with proof of purchase. This warranty applies to the original purchaser only and is
non-transferable. Meade products purchased outside North America are not included in this warranty, but are covered under
separate warranties issued by Meade international distributors.
RGA Number Required: Prior to the return of any product or part, a Return Goods Authorization (RGA) number must be
obtained from Meade by writing, or by calling (949) 451-1450. Each returned part or product must include a written statement
detailing the nature of the claimed defect, as well as the owner’s name, address, and phone number.
This warranty is not valid in cases where the product has been abused or mishandled, where unauthorized repairs have been
attempted or performed, or where depreciation of the product is due to normal wear-and-tear. Meade specifically disclaims
special, indirect, or consequential damages or lost profit which may result from a breach of this warranty. Any implied
warranties which can not be disclaimed are hereby limited to a term of one year from the date of original retail purchase.
This warranty gives you specific rights. You may have other rights, which vary from state to state.
Meade reserves the right to change product specifications or to discontinue products without notice.
This warranty supersedes all previous Meade product warranties.

WARNING
This equipment has been tested and found to comply with the limits for a CLASS B digital device, pursuant to Part 15 of
the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential
installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions contained in this manual, may cause harmful interference to radio and television
communications. However, there is no guarantee that interference will not occur in a particular installation.
If this equipment does cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following
measures:
•
•
•
•

Reorient or relocate the receiving antenna.
Increase the separation between the equipment and the receiver.
Connect the equipment into an outlet on a circuit different from that of the receiver.
Consult the dealer or an experienced audio television technician.

NOTE: Connecting this device to peripheral devices that do not comply with CLASS B requirements or using an
unshielded peripheral data cable could also result in harmful interference to radio or television reception.
The user is cautioned that any changes or modifications not expressly approved by the party responsible for compliance
could void the user’s authority to operate this equipment.
To ensure that the use of this product does not contribute to interference, it is necessary to use shielded I/O cables.

Meade Instruments Corporation
6001 OAK CANYON, IRVINE, CALIFORNIA 92618-5200 U.S.A.
(949) 451-1450
Ver. 0300

FAX: (949) 451-1460

www.meade.com

ETX® is a registered trademark of Meade Instruments Corporation.

Part no. 14-1010-20

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