Instruction Manual
ETX-90EC Astro TelescopeETX-105EC Astro TelescopeETX-125EC Astro Telescope

Meade Instruments Corporation

CONTENTSWARNING!
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 theobserver that damage has occurred until it is
too late. Do not point the telescope or its
viewfinder at or near the Sun. Do not lookthrough the telescope or its viewfinder as it ismoving. Children should always have adultsupervision while observing.

CAUTION!
Use care to install batteries as indicated by
the battery compartment. Follow battery
manufacturer's precautions. Do not installbatteries backward or mix new and usedbatteries. Do not mix battery types. If theseprecautions are not followed, batteries may
explode, catch fire, or leak. Improperly
installed batteries void your Meade warranty.

Quick-Start Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Telescope Electronic Controller Functions . . . . . . . . .5
ETX: Your Personal Window on the Universe . . . . . . .6
Telescope Controls . . . . . . . . . . . . . . . . . . . . . . . . . .6
Electronic Controller Functions . . . . . . . . . . . . . . . . . .8
Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Parts Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Assembly Instructions . . . . . . . . . . . . . . . . . . . . . . . .9
Using the Viewfinder . . . . . . . . . . . . . . . . . . . . . . . .10
Focusing the Viewfinder . . . . . . . . . . . . . . . . . . .10
Aligning the Viewfinder . . . . . . . . . . . . . . . . . . . .10
Observation Techniques . . . . . . . . . . . . . . . . . . . . . . .11
Choosing an Eyepiece . . . . . . . . . . . . . . . . . . . . . . .11
Understanding Magnification . . . . . . . . . . . . . . . . . .12
Terrestrial Observing . . . . . . . . . . . . . . . . . . . . . . . .12
Astronomical Observing . . . . . . . . . . . . . . . . . . . . . .13
Sidereal Rate . . . . . . . . . . . . . . . . . . . . . . . . . . .13
The Electronic Controller . . . . . . . . . . . . . . . . . . . . .13
Slew Speeds . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Modes of Operation . . . . . . . . . . . . . . . . . . . . . .14
Telescope Mountings . . . . . . . . . . . . . . . . . . . . . . . .14
Alt/Az Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Polar Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Celestial Coordinates . . . . . . . . . . . . . . . . . . . . .16
Locating the Celestial Pole . . . . . . . . . . . . . . . . .16
Polar Alignment Procedure . . . . . . . . . . . . . . . . .16
Photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
A Few Tips on Photography . . . . . . . . . . . . . . . . . . .19
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . .20

If you are anxious to use your ETX Astro
Telescope for the first time, before athorough reading of this instruction manual,
see the QUICK-START GUIDE on page 4.

General Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . .22
Storage and Transport . . . . . . . . . . . . . . . . . . . . . . .22
Inspecting the Optics . . . . . . . . . . . . . . . . . . . . . . . .23
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Meade Customer Service . . . . . . . . . . . . . . . . . . . . .24
Telescope Specifications . . . . . . . . . . . . . . . . . . . . .25
Appendix A: Advanced Controller Functions . . . . . . .26
Tracking Motor Speed . . . . . . . . . . . . . . . . . . . . . . .26
Changing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Appendix B: Helpful Charts . . . . . . . . . . . . . . . . . . . .27
Latitude Chart for Major Cities of the World . . . .27
Star Locator . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Appendix C: Polar Alignment; Setting Circles . . . . . .28
Precise Polar Alignment . . . . . . . . . . . . . . . . . . .28
Setting Circles . . . . . . . . . . . . . . . . . . . . . . . . . .28
Appendix D: You and the Universe . . . . . . . . . . . . . . .29
Objects in Space . . . . . . . . . . . . . . . . . . . . . . . . . . .29
The Moon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Planets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Deep-Sky Objects . . . . . . . . . . . . . . . . . . . . . . . .30® The name “Meade,” the Meade logo, and “ETX” aretrademarks registered with the U.S. Patent Office and inprincipal countries throughout the world. All rights reserved.
© 2001 Meade Instruments Corporation.

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QUICK-START GUIDE
1

A

4

B

G

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 their respective attachment screws to a
firm feel only.

2

E

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

5
H

C

Slew Speed:
FastMediumModerate
Slow
I

D

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

3

F

G

NOTE: The
telescope hasrotational hardstops in thehorizontal andvertical axes toprevent damage tothe telescope. See
page 6, for more
information.

Use the Electronic Controller Arrow keys (H) to movethe telescope up, down, left, and/or 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.

6

NOTE: Before
observing, verify
that the flip-mirror
control (14, Fig. 1)
is in the “up”
position. See FLIPMIRROR CONTROL,
page 7, 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
9, Fig. 1) and then remove the dust cover (19, Fig. 1)
from the end of the telescope tube.

Sight along the side of the telescope’s main tube tolocate an object. Practice using the Electronic
Controller Arrow keys to center an object in thetelescope’s field of view. Use the telescope’s focus
knob (8, Fig. 1) to bring the object into focus.

TELESCOPE AND ELECTRONIC CONTROLLER FUNCTIONS
18

1

4

3

2

5

Features of the ETX-90EC, ETX105EC, and ETX-125EC are
identical, with the exception of
the size of optical tube and thetype of viewfinder included as
standard equipment.

17

19

16

6

(on leftfork arm)

15

7

14

8

13

9
12
10
11
20

E

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

B

C

D

A

B

Fig. 1 (Inset): Computer Control Panel. (A) On/Off switch;(B) Auxiliary ports; (C) Handbox port; (D) 12v connector; (E)Power indicator light.

-5-

ETX: Your Personal Window to the Universe
The Meade ETX-90EC, ETX-105EC, and the ETX-125EC are extremely versatile, high-resolution
telescopes with features similar to those once available only with larger and more specialized imaging
systems. 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.
Your ETX telescope reveals nature in an ever-expanding level of detail. Observe the feather structure of aneagle from 50 yards or study the rings of the planet Saturn from a distance of 800 million miles. Focus
beyond the Solar System and observe majestic nebulae, ancient star clusters, remote galaxies, and evenstars recently discovered to have planets orbiting about them. Meade ETX telescopes are instruments fully
capable of growing with your interest and are ideal for both the casual observer and serious astronomer
alike.

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.

Eyepiece - Place the supplied SP 26mm eyepiece into the 90° Eyepiece Holder (4, Fig. 1) and tighten inplace with thumbscrew (3, Fig.1).



Viewfinder a.

ETX-90EC: 8 x 21mm Viewfinder: Slide the eyepiece end of the viewfinder through the front of
the viewfinder bracket (1, Fig. 5).

b.

ETX-105EC, ETX-125EC: 8 x 25mm Right-Angle Viewfinder: Slide the front cell end of theright-angle viewfinder through the rear of the viewfinder bracket (2, Fig. 5).

Eyepiece Holder Thumbscrew - Tightens the eyepiece in place. Tighten to a firm feel only.

90° Eyepiece Holder - Holds the eyepiece upright for easy viewing.

Optical Tube - The main optical component that gathers the light from distant objects and brings thislight to a focus for examination with the eyepiece.



Vertical Lock - Controls the manual vertical movement of the telescope. Turning the vertical lockcounterclockwise 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 polaraligned, the vertical lock serves as the Declination, or Dec. lock (see DECLINATION, page 16).
Note: The vertical lock knob is a knurled knob located on the fork arm to the right of the focus
knob (8, Fig. 1). Mounted beneath the knob is a circular scale with no numbers. Do not confuse
this scale with the Dec. setting circle (16, Fig. 1) on the opposite fork arm which has anumbered scale used to locate astronomical objects.
CAUTION: When loosening the vertical lock, be sure to support the optical tube (5, Fig. 1). The
tube may swing downward suddenly and damage the telescope.

Fork Arms - Hold the optical tube in place.
Note: The telescope base and fork mount are designed with internal “rotational limit stops.”
The horizontal limit stop prevents the telescope from rotating more than 360° 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 fromcontacting the base if pointed downward more than 30°. Do not force the telescope to movebeyond these stops or damage to the telescope will result.
Focus Knob - Moves the telescope’s optical tube (5, Fig. 1) in a finely-controlled motion to achieveprecise image focus. The ETX telescopes can be focused on objects from a distance of about 11.5 ft(ETX-90EC) or 15 ft (ETX-105EC or ETX-125EC) to infinity. Rotate the focus knob clockwise to focus
on distant objects, and counterclockwise to focus on nearby objects.
Horizontal Lock - Controls the manual horizontal rotation of the telescope. Loosen the horizontal lockcounterclockwise to unlock the telescope, enabling it to be freely rotated by hand about the horizontal
axis. Tightening 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, thehorizontal lock serves as the Right Ascension, or R.A. lock (see RIGHT ASCENSION, page 16).

-6-

Computer Control Panel
A. ON/OFF Switch - Turns the Computer Control Panel and Electronic Controller ON or OFF.
Note: Always remove the batteries if they are not to be used for a long period of time.
B. Auxiliary (AUX) Ports (2) - Provide connection for current and future Meade accessories,
such as the Meade “AstroFinder Software with #505 Cable Connector Kit,” which allows you tocontrol your ETX from a PC. See OPTIONAL ACCESSORIES, page 20.
C. Handbox (HBX) Port handbox into this port.

Plug the Electronic Controller or the optional #497 Autostar

D. 12v: The 12v connector is designed to accept an external power supply such as theoptional #541 AC Adapter or the #607 Power Cord (see OPTIONAL ACCESSORIES, page20). When one of the external power supply options is used, the internal batteries are
disconnected from the power circuit.
E. LED - The red power indicator light illuminates when power is supplied to the connected
handbox and to the telescope’s motor drive.
Base Housing - Supports the telescope for placement on a flat, level surface, such as a tabletop or
optional tripod. See OPTIONAL ACCESSORIES, page 20.
Holes for Optional Tripod - See your tripod’s instruction sheet for mounting information.



Right Ascension (R.A.) Setting Circle - See page 28 for detailed information.

Flip-Mirror and Flip-Mirror Control Knobs - ETX telescopes include an internal mirror. With the flipmirror control in the “up” position, as shown in Fig. 2a, light is diverted to the eyepiece. With the flipmirror control in the “down” position, as shown in Fig. 2b, light proceeds straight out the photo port forphotography. See PHOTOGRAPHY, page 18.
Note: The flip-mirror control is in the “up” position when the control is vertical (perpendicular
to the telescope tube). To place the flip-mirror in the “down” position, turn the control until it ishorizontal.

Fig. 2a: Flip mirror
control in the “up”
position.



Photo Port - Attach any 35mm camera with a removable lens to this port using an optional #64ST TAdapter or attach the #932 Erecting Prism for correctly oriented images through the eyepiece. See
OPTIONAL ACCESSORIES, page 20.

Declination (Dec.) Setting Circle (on left fork arm) - See page 28 for detailed information.



Viewfinder Alignment Screws -Adjust these screws to align the viewfinder. See pages 9 through 11
for more information.



Viewfinder Alignment Bracket -Attach the viewfinder to this bracket. See pages 9 through 11 formore information.



Dust Cap - Unthread the dust cap counterclockwise from the front lens of the telescope.
Note: The dust cap should be replaced after each observing session and the power turned off
to the telescope. Verify that any dew that might have collected during the observing session
has evaporated prior to replacing the dust cap. Do not overtighten.

Fig. 2b: Flip mirror
control in the “down”
position.

Battery Compartment (not shown, underneath base) - Install eight user-supplied AA batteries in thiscompartment. See page 9 for more information.

-7-

Electronic Controller Functions


Fast



MediumModerate




Slow






Fig. 3: Electronic Controller. (1) Arrow Keys; (2) Indicator
Lights; (3) SPEED Key; (4) Coil Cord; (5) MODE Key; (6) OUT
Key; (7) IN Key.
The Electronic Controller provides you with the means to control the telescope motors from a compact
handbox. The Electronic Controller (Fig. 3) has soft-touch keys designed to have a positive feel, eventhrough gloves.
The primary functions of the Electronic Controller are to move (slew) the telescope to an object, indicate theslew speed, and to operate the optional #1244 (ETX-90EC or ETX-105EC) or #1247 (ETX-125EC) Electric
Focuser (see OPTIONAL ACCESSORIES, page 20). Other functions are also possible when using the MODE
key. A detailed description of the functions and operation of the Electronic Controller is found in ADVANCEDELECTRONIC CONTROLLER FUNCTIONS, page 26.
Arrow Keys (1, Fig. 3): Press one of the four Arrow keys to slew the telescope (i.e., up, down, left,
and right) at any one of four slew speeds (see SPEED KEY below).
Important Note: If you reverse directions while using the Arrow keys to slew to objects, there
may be a slight pause as the telescope motors compensate for the reversal of the internal
gears.

Light No.
Light 1
Light 2
Light 3

Light StatusOn

Note: For purposes of this manual, the lights are identified as 1 through 4, with 1 being the top lightand 4 being the bottom light.

Blinking
OffSPEED Key (3, Fig. 3): Press the SPEED key to change the speed at which the telescope slews to an

object. 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. 3).

Light 4
Indicator Light Key
The procedures in this manual
identify the status of the four
indicator lights as depictedabove: on, blinking, or off.

Indicator Lights (2, Fig. 3): The four red LED (Light Emitting Diode) lights indicate the current slew
speed of the telescope.



Coil Cord: Plug into the HBX connector of the Computer Control Panel.



MODE Key (5, Fig. 3): Press and hold the MODE key to place the Electronic Controller into the Modefunction (see APPENDIX A, page 26).


OUT Key (6, Fig. 3): When using the optional #1244 (ETX-90EC or ETX-105EC) or #1247 (ETX-

125EC) Electric Focuser (see OPTIONAL ACCESSORIES, page 20), press the OUT key to move thefocus point outward.
IN Key (7, Fig. 3): When using the optional #1244 (ETX-90EC or ETX-105EC) or #1247 (ETX-125EC)

Electric Focuser (see OPTIONAL ACCESSORIES, page 20), press the IN key to move the focus point
inward.

-8-

GETTING STARTED
Parts List
ETX telescopes are assembled virtuallycomplete at the Meade factory. Getting thetelescope ready for first observations
requires only a few minutes. When first
opening the packing box, note carefully thefollowing parts:• The ETX Astro Telescope with forkmount system.
• Electronic Controller with attached coil
cord.
• Viewfinder.
• Super Plössl (SP) 26mm eyepiece,
packed in a plastic storage container.
• Hex-wrench set (2 wrenches), packed
with the manual.
The viewfinder is packed separately fromthe main telescope to avoid the possibilityof the viewfinder slipping in its bracket andscratching during shipment.

Assembly Instructions
Assembly of your telescope requires thefollowing procedures: install batteries,
insert an eyepiece, attach the viewfinder,
and plug in the handbox.

1
2

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.

Install the Batteries
Assembly of all three of the ETX model telescopes requires eight user-supplied AA-size batteries and thefollowing steps:
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 thetwo 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
FOR BEGINNERS
battery mounting board. Slide and snap thecover back in place. Return the telescope
to an upright position.

TIPS

Insert an Eyepiece
Remove the SP 26mm eyepiece (1, Fig. 1)
from its container and place it in theeyepiece holder (4, Fig. 1). Tighten the
thumbscrew (3, Fig. 1) to a firm feel only.

Plug in the Handbox
Be certain that the power switch on theComputer Control panel (10A, Fig. 1) is in
the OFF position. Plug the coil cord of theElectronic Controller into the HBX port
(10C, Fig. 1).

Attach the Viewfinder
ETX-90EC: 8 x 21mm Viewfinder: Slide
the eyepiece end of the viewfinder throughthe front of the viewfinder bracket (1, Fig.
5).
ETX-105EC or 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. 5).
Unthread the six alignment screws slightly
to fit the viewfinder through the bracket.
With the viewfinder in place, tighten the sixalignment screws to a firm feel only against
the viewfinder tube.

-9-

Join an Astronomy Club
Attend a Star Party

One fun way to learn about astronomy is to join an
astronomy club. Check your local newspaper,school, library, or telescope dealer/store to find out
if there’s a club in your area.
At club meetings, you will meet other astronomy
enthusiasts with whom you will be able to shareyour discoveries. Clubs are an excellent way tolearn more about observing the sky, to find out
where the best observing sites are, and to compare
notes about telescopes, eyepieces, filters, tripods,
and so forth.
Often, club members are excellent photographers.
Not only will you be able to see examples of theirart, but you may even be able to pick up some“tricks of the trade” to try out on your ETX
telescope. See page 18 for more information aboutphotography with the ETX.
Many groups also hold regularly scheduled Star
Parties at which you can check out and observewith many different telescopes and other pieces ofastronomical equipment. Magazines such as Sky &Telescope and Astronomy print schedules for many
popular Star Parties around the United States andCanada.

Using The Viewfinder
As with most astronomical telescopes,
the ETX model telescopes present a
fairly narrow field of view to the observer.
As a result it is sometimes difficult tolocate and center objects in thetelescope’s field of view. The viewfinder,
by contrast, is a low-power, wide-fieldsighting scope with crosshairs that let
you easily center objects in the eyepieceof the main telescope’s field of view. The
telescope viewfinder is a great help in
locating faint astronomical objects before
you begin observing through thetelescope eyepiece.

1
ETX-90EC Viewfinder2
ETX-105EC/-125EC Right-Angle Viewfinder

Fig. 5: Viewfinder Installation.

ETX-90EC 8 x 21mm Erect-Image Viewfinder:Standard equipment with the ETX-90EC, the 8 x 21mm Erect-Image Viewfinder has 8-power magnification
and an aperture of 21mm. This viewfinder presents a correctly oriented image both up-and-down andleft-to-right.
ETX-105EC or ETX-125EC 8 x 25mm Right-Angle Viewfinder:Standard equipment with the ETX-105EC and ETX-125EC, the 8 x 25mm Right-Angle Viewfinder has 8power magnification and an aperture of 25mm. This viewfinder presents a correctly oriented image upand-down, but is reversed left-for-right.

Focusing the Viewfinder
The ETX model viewfinders are pre-focused at the factory. Individual eye variations may require that the
viewfinder be re-focused. To check the focus, point the viewfinder at a distant terrestrial (land) object suchas a telephone pole or light pole and look through the viewfinder. If the viewfinder image is not in sharp
focus, follow the procedure below that applies to your telescope model.
ETX-90EC
1. Remove the viewfinder by slightly unthreading the six alignment screws (4 and 6, Fig. 6) and slipping it
out of the bracket.
2. Loosen the knurled lock-ring (2, Fig. 6) located near the viewfinder’s front lens cell (1, Fig. 6). 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 directionor the other, until the object appears sharp. One or two rotations of the lens may have a significant effecton image focus.
4. Lock the focus in place by threading the knurled lock-ring clockwise up against the viewfinder’s lens cell.
5. Replace the viewfinder into the viewfinder bracket. Gently tighten the six alignment screws. Proceed with
Aligning the Viewfinder.
ETX-105EC or ETX-125EC

3

Turn the focus ring (2, Fig. 6) at the baseof the viewfinder eyepiece (3, Fig. 6) ineither direction until a sharp focus isreached.

2

4

Aligning the Viewfinder

ETX-125EC

In order for the viewfinder to be useful, it
must first be aligned with the main
telescope, so that both the viewfinder andthe main telescope are pointing at
precisely the same location. To align the
viewfinder:
1. Turn the three rear alignment screwsof the viewfinder bracket (6, Fig. 6) sothat the viewfinder tube is roughly
centered within the viewfinder bracket.
Tip: Do not overtighten the alignment screws. When tightening one
screw it may be necessary to loosen
one or both of the two otheralignment screws.
- 10 -

5

1

ETX-90EC

2

3

6

Fig. 6: The Viewfinder. (1) Front lens cell; (2) Knurled lockring (ETX-90EC) or focus ring (ETX-105EC and ETX125EC); (3) Viewfinder eyepiece; (4) Front alignment screws(one not visible in photo); (5) Viewfinder bracket; (6) Rearalignment screws (one not visible).

2. Point the main telescope at someeasy-to-find, well-defined land object,such as the top of a telephone pole.
Center the object, as precisely as
possible, in the SP 26mm eyepiece's
field of view, then tighten the verticaland horizontal locks (6 and 9, Fig. 1)
so that the tube cannot move and theobject remains centered (1, Fig. 7).
3. While looking through the viewfinder,
turn one or more of the three front
viewfinder alignment screws (4, Fig.
6), until the crosshairs of the viewfinder point at precisely the same
position as the view through theeyepiece of the main telescope(2, Fig. 7).

(beforealignment)

1

View through the
viewfinder

View through thetelescope eyepiece(afteralignment)

2

Check that the viewfinder’s crosshairs Fig. 7: Aligning the Viewfinder.
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.
Tip: If you plan on viewing using higher magnification eyepieces, first locate, center, and focus
the object using a low-power eyepiece (e.g., SP 26mm eyepiece). Then remove the low-power
eyepiece and replace it with a higher-power eyepiece; the object should still be centered in thefield of view. Objects are much easier to locate and center at lower powers; higher powers are
employed simply by changing eyepieces.

OBSERVATION TECHNIQUESThe 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
A telescope’s eyepiece magnifies the image
formed by the telescope’s main optics. Eacheyepiece has a focal length, expressed inmillimeters, or “mm.” The smaller the focal
length, the higher the magnification. For
example, an eyepiece with a focal length of
9mm has a higher magnification than an
eyepiece with a focal length of 26mm.
The SP 26mm eyepiece, supplied with yourtelescope, gives a wide, comfortable field ofview with high image resolution, while anoptional SP 12.4mm eyepiece, for example,
provides a smaller field of view but higher
magnification when seeing conditions permit.
Low-power eyepieces offer a wide field ofview, bright, high-contrast images, and lesseyestrain during long observing sessions. To
find an object with a telescope, always startwith a low-power eyepiece such as the SP
26mm. When the object is located andcentered in the eyepiece, you may wish toswitch to a higher-power eyepiece to enlarge
the image as much as practical for prevailingseeing conditions.
Note: Seeing conditions vary widely fromnight-to-night and from site-to-site.
Turbulence in the air, even on anapparently clear night, can distort images.
If an image appears fuzzy and ill-defined,back off to a lower-power eyepiece for amore well-resolved image (Fig. 8a and 7b).

- 11 -

TIPS FOR BEGINNERS
Too Much Power?
Can you ever have too much power? If the type of
power you’re referring to is eyepiece magnification,
yes, you can! The most common mistake of the
beginning observer is to “overpower” his or her
telescope by using high magnifications which thetelescope’s aperture and atmospheric conditions
cannot reasonably support. Keep in mind that asmaller, but bright and well-resolved image is far
superior to one that is larger, but dim and poorly
resolved (see below). Powers above 300X shouldbe employed only under the steadiest atmosphericconditions.
Most observers should have three or four additional
eyepieces to achieve the full range of reasonablemagnifications possible with the ETX telescopes.
See OPTIONAL ACCESSORIES, page 20.

Fig. 8a & b: Jupiter; example of too much magnification.

Understanding Magnification
The magnification, or power, at which a telescope is operating is determined by two factors: the focal lengthof the telescope and the focal length of the eyepiece employed.
Telescope Focal Length is the distance that light travels inside the telescope before reaching a focus. In
the mirror-lens design of the ETX models, however, this focal length is, in effect, compressed by thetelescope’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 werea classical refracting-type of telescope, the optical tube would be more than four feet long instead of theETX–90EC's compact 11” tube length.
Eyepiece Focal Length is the distance light travels inside the eyepiece before reaching focus. Focal lengthis usually printed on the side of the eyepiece. For instance, the Super Plössl (SP) 26mm eyepiece suppliedwith the three ETX models has a focal length of 26mm. “Super Plössl” refers to the optical design of theeyepiece, a design specifically intended for high-performance telescopes and one which yields a wide,
comfortable field of view with extremely high image resolution.
Technical note to the advanced amateur astronomer: The SP 26mm eyepiece supplied with
the Meade ETX-90EC, ETX-105EC, and ETX-125EC is a special low-profile version of thestandard Meade SP 26mm eyepiece which is about 1/4” (6mm) shorter than the standard
eyepiece. This low-profile SP 26mm is designed to work in harmony with the ultracompact scaleof the 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., theeyepiece requires re-focusing when it is interchanged with other SP eyepieces).
Calculating Magnification: On a telescope, such as the ETX, different eyepiece focal lengths are used toachieve different magnifications, from low to high. The standard-equipment SP 26mm eyepiece yields 48X(“48-power”) on the ETX-90EC, 57X on the ETX-105EC, and 73X on the ETX-125EC. A variety of powers
may be obtained with the addition of optional eyepieces as well as the #126 2X Barlow Lens which doubles
the power of an eyepiece (see OPTIONAL ACCESSORIES, page 20).

Telescope Focal Length
Power = ____________________
Eyepiece Focal Length
Example: To obtain the power of an ETX-125EC (which has a 1900mm focal length) using a
SP 26mm eyepiece:
1900mmPower = ________ = 73X
26mm

Terrestrial Observing
All three of the ETX models make excellent, high-resolution terrestrial (land) telescopes. When you set thetelescope on its drive base, as shown below in Fig. 9, you may use it for an extremely wide range of
observations. When you look through the eyepiece at a terrestrial object, you will notice that the image isright-side-up, but reversed left-for-right. 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 OPTIONALACCESSORIES, page 20).
Viewing terrestrial objects requires
looking along the Earth's surface throughheat waves. Heat waves often degrade
image quality. Low-power eyepieces, likethe SP 26mm eyepiece, magnify theseheat waves less than higher-power
eyepieces.
Therefore,
low-power
eyepieces provide a steadier, higherquality image. If the image in an
eyepiece is fuzzy or ill-defined, reduce toa lower power. Observing in the early

AzimuthAltitude

Note:
Throughout this manual,
you will notice the term
"Alt/Az." Alt/Az is
frequently used to refer
to altitude or verticaland azimuth orhorizontal. Alt/Az is justone of many methods
used by amateur
astronomers to help
locate stars in the nightsky.

Use this formula to calculate the magnification obtained with a given eyepiece:
Most observers should have 3 or 4 eyepieces plus the #126 2X Barlow to achieve the full range ofreasonable magnifications possible with ETX models.

Fig. 9: Alt/Az mounting moves the telescope in vertical andhorizontal directions.

- 12 -

gh

t

ce

ns

io

n

cli

Ri

As

De

ris
la
Po

morning hours, before the ground has
built up internal heat, results in better
viewing conditions than during the lateafternoon hours.

na
tio
n

If you wish to observe a distant land
object, such as a mountain top or a bird,
you can observe by merely pointing thetelescope and looking through theeyepiece. Set the telescope on a table
top or tripod, loosen the horizontal andvertical locks (6 and 9, Fig. 1), and turnthe telescope towards the object you Fig. 10: Equatorial mounting aligns the telescope with thewish to observe. Look into the viewfinder celestial sphere (table-top tripod legs optional).
and move the tube until you find theobject. If the viewfinder is correctlyaligned, the object now appears in the eyepiece. Center the object and focus the image using the by turning
the focus knob (8, Fig. 1). Rotate the knob clockwise to focus on distant objects and counterclockwise tofocus on nearby objects.

Astronomical Observing
As an astronomical instrument, your ETX telescope has many optical and electromechanical capabilities. It
is in astronomical applications where the high level of optical performance is readily visible. The range of
observable astronomical objects is, with minor qualification, limited only by the observer’s motivation.

Sidereal RateAs the Earth rotates beneath the night sky, the stars appear to move from East to West. The speed at which
the stars move across the sky is called the sidereal rate.
You can observe stars and objects in the night sky using the terrestrial viewing method, but note that objects
begin to slowly drift across and out of the eyepiece field. This motion is caused by the rotation of the Earth.
You can counteract the drift by mounting thetelescope to one of the optional tripods in thepolar mode (see POLAR ALIGNMENTPROCEDURE, page 16). In this mode, themotor drive in each ETX model is designed torotate the telescope at the sidereal rate so thatit automatically follows, that is, "tracks" thestars. Tracking makes it easier to locate
objects and to keep them centered in thetelescope’s eyepiece. The Electronic
Controller supplied with your telescope assists
with the tracking function.

TIPS FOR BEGINNERS•

Try to pick an observing site away from street
and house lights, and car headlights. While
this is not always possible, the darker the site,
the better.

•

Give your eyes about ten minutes to adjust to
the darkness before observing. Give your eyesa rest from observing every ten or fifteen
minutes to relieve eyestrain.

•
Functions of the Electronic Controller include:• Slewing (moving) the telescope's opticaltube assembly to an object• Turning on the telescope motor drive toautomatically track celestial objects (whenthe telescope is polar aligned)• Changing the hemisphere of operation,
when required• Changing tracking speed (see APPENDIX A,
page 26)

Try not to use a standard flashlight. Seasoned
observers use red LED flashlights or tape redcellophane over their flashlights for setup andmap reading so they don’t have to continually
readjust their eyes to the darkness. Be careful
not to shine bright lights if there are otherobservers in the area. Never shine a flashlightinto a telescope while someone is observing!

•

Dress warmly. It gets chilly when you’re sitting
for prolonged periods, even on some summernights.

•Practice setting up your equipment during the
day or in a lighted area to become familiar with
it before going to a dark site.

Slew Speeds•

Use your 26mm eyepiece to view terrestrial
objects and wider areas of space, such as
open star clusters. Use your higher power
eyepieces when you wish to view something
up close, such as craters on the Moon or the
rings of Saturn.

•

Know your observing site. If you’re going to try
out an unfamiliar site, check it out in the daylightfor possible obstructions and pitfalls.

The Electronic Controller

Fig. 11: Electronic
Controller.

The Electronic Controller has four slew
speeds that are directly proportional to thesidereal rate. Press the Speed key to change
the slew speed. Note each slew speed
corresponds to one of the four LED's of theElectronic Controller.

- 13 -

Light 1 (top LED): The fastest speed. Use to move the telescope quickly from one point in the sky toanother.
Light 2: Best for centering an object in the viewfinder.
Light 3: Best for centering an object in the field of a low-to-moderate power eyepiece, such as the standard
SP 26mm.
Light 4: The slowest speed. Use to center an object in the field of view of high-power eyepieces, such as
the optional 6.7mm or 12.4mm.
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) can be used for pushbutton (manual) tracking of astronomical
objects while observing through the eyepiece.

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 below) and the polar mode (used when thetelescope is polar- (or equatorial) aligned; see page 16).
• Choose the Alt/Az (altitude-azimuth, or vertical-horizontal) mode for all terrestrial operations of thetelescope. In the Alt/Az mode, use the Arrow keys to slew the telescope to terrestrial or astronomical
objects and, once you locate them, follow these objects if they move. However, in this mode astronomical
tracking is not automatic and requires continuous pushes of the Arrow keys. The Electronic Controller isfactory pre-set to the Alt/Az mode.
• Choose the polar mode when the telescope is equipped with either the optional #880 (ETX–90EC) or #881
(ETX-105EC or ETX-125EC) Table Tripod, or #883 Deluxe Field Tripod, for extensive astronomical
observations. In this mode use the Arrow keys to slew the telescope to objects. In addition, the telescope’s
internal motor drive is turned on, enabling the telescope to automatically track celestial objects.
You can configure the two screws on the bottom rear of the Electronic Controller handbox to change thedefault mode of the Electronic Controller to Alt/Az or polar. When in polar mode, you may also set thealignment to the hemisphere in which you are located (not necessary in the Alt-Az mode).
Caution: 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 therecess.
• Remove mode screw A (1, Fig. 12) to make the Northern hemisphere polar mode the automatic defaultof the Electronic Controller when power is applied (i.e., the motor drive is activated for operation in the
Earth’s Northern Hemisphere).
• Remove mode screw B (2, Fig. 12) to make the Southern Hemisphere polar mode the automatic defaultof the Electronic Controller when power is applied (i.e., the motor drive is activated for operation in the
Earth’s Southern Hemisphere ).
• Leave both the A and B screws in place (or remove both screws) to keep the telescope in the original
factory default Alt/Az mode.
Note: Removing either A or B screw affects only the telescope’s default mode; you may still makemode changes when desired using the MODE key (see, APPENDIX A, page 26).

Telescope Mountings
A mount allows a telescope to move on
its axes. The two basic types ofmounting are Altazimuth (Alt/Az) andPolar (Equatorial).

Meade Instruments Corporation

35-4702-00
CC
Tested to comply
with FCC Standards

C
FC

A

Alt/Az Mode
Altazimuth (Alt/Az) mounting permits
movement of the telescope tube invertical (altitude) and horizontal(azimuth) directions. The ETX models
incorporate an altazimuth mount (asshown in Fig. 9), ideal for terrestrial

FOR HOME OR OFFICE USE

B

1Fig. 12: Mode screws on rear of Electronic Controller.
(1) Mode screw A; (2) Mode screw B.

- 14 -

2

applications and for casual astronomical observation. The telescope may be placed on a rigid tabletop oron the optional Meade #883 Deluxe Field Tripod (see OPTIONAL ACCESSORIES, page 20) to provide asecure, variable-height, altazimuth observing platform. To manually track objects with the telescope in thealtazimuth configuration, press the Arrow keys of the Electronic Controller as necessary to keep an object
centered.
Note: Automatic tracking of objects is not possible with the ETX-90 EC, ETX-105EC and the ETX125EC in the Alt/Az mounting.
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 (seeOPTIONAL ACCESSORIES, page 20).

2.

Insert a low-power eyepiece (e.g., SP 26mm) into the eyepiece holder (4, Fig. 1) and tighten theeyepiece thumbscrew (3, Fig. 1).

3.

Tighten the vertical and horizontal locks (6 and 9, Fig. 1), if necessary.

4.

Verify that the power switch (10A, Fig. 1) on the telescope’s Computer Control panel is OFF.

5.

Plug in the Electronic Controller coil cord (4, Fig. 3) to the HBX port (10C, Fig. 1) on the Computer
Control panel.

6.

Flip the power switch to ON. The power indicator (10E, Fig. 1) on the Computer Control panel lights
and all four speed indicators (2, Fig. 3) blink rapidly.

7.

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

8.

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

9.

Use the four Arrow keys (1, Fig. 3) to slew
the telescope to the desired object. Tochange the slew speed, press the SPEED
key.

10. Fine-adjust the position of the object with
the Electronic Controller Arrow keys sothat it is centered in the viewfinder. The
object is now ready to be viewed throughthe telescope’s eyepiece.

Polar ModeIf you are to use your ETX-90EC, ETX-105EC,
or ETX-125EC telescope for extensive
astronomical applications, it is recommended
you use Polar or Equatorial mounting. By
tilting one of the telescope’s mechanical axes
(see Fig. 10) to point at the celestial pole (i.e.,by pointing one axis of the telescope to theNorth Star, Polaris), you may follow (track)
astronomical objects through the sky.
The telescope's optical tube turns on only one
axis of the telescope instead of simultaneously
turning on two axes, as required of the
Altazimuth mount. An Equatorial mount which
has one of its axes (the polar axis) pointing to thecelestial pole is said to be polar aligned. The ETXmodels can be polar aligned either by using theoptional #883 Deluxe Field Tripod or the table
tripod specific to your model of ETX telescope(see OPTIONAL ACCESSORIES, page 20).
With the ETX polar aligned, the telescope’s
internal motor drive may be activated (seeAPPENDIX A, page 26) to enable fully automatic
hands-off tracking of celestial objects. In this- 15 -

TIPS FOR BEGINNERS
Surf the Web
One of the most exciting resources for astronomy is
the Internet. The Internet is full of websites withnew images, discoveries, and the latest
astronomical information. For example, whencomet Hale-Bopp made its approach to our Sun in
1998, astronomers around the world posted new
photos daily.
You can find websites for virtually any topic relating
to astronomy on the internet. Try the following key
word searches: NASA, Hubble, HST, astronomy,
Messier, satellite, nebula, black hole, variable stars,
extrasolar, Chandra, gamma burster, etc.
Check out Meade’s website for the latest productand technical information. You can download thelatest software revisions, links to otherastronomical sites, coordinates of celestial objects
and the latest satellite tracking information for the
optional #497 Autostar handset. See page 20 for
more information. You’ll find our website at:
http://www.meade.com/
Here are some other sites you might find useful:• Sky & Telescope:
http://www.skypub.com/• Astronomy:
http://www.astronomy.com/astro/• The Starfield:
http://users.nac.net/gburke/• Astronomy Picture of the Day:
http://antwrp.gsfc.nasa.goc/apod/• Heavens Above (satellite observing information):
http://www.heavens-above.com/• Photographic Atlas of the Moon:
http://www.lpi.ursa.edu/research/lunar_orbiter• Hubble Space Telescope Public Picturesconfiguration the observer does not need to press the Arrow keys of the Electronic Controller in order totrack celestial objects. However, 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 move the telescope over thesurface of the Moon or through a large star field.

Celestial Coordinates
Before polar aligning your ETX model, it is helpful to understand how to locate celestial objects as they
move across the sky.
A celestial coordinate system was created that maps an imaginary sphere surrounding the Earth upon which
all stars appear to be placed. This mapping system is similar to the system of latitude and longitude on Earthsurface maps.
In mapping the surface of the Earth, lines of longitude are drawn between the North and South Poles andlines of latitude are drawn in an East-West direction, parallel to the Earth’s equator. Similarly, imaginary lines
have been drawn to form a latitude and longitude grid for the celestial sphere. These lines are known as
Right Ascension and Declination.
The celestial map also contains two poles and an equator just like a map of the Earth. The poles of thiscoordinate system are defined as those two points where the Earth’s north and south poles (i.e., the Earth'saxis), if extended to infinity, would cross the celestial sphere. Thus, the North Celestial Pole (1, Fig. 13) isthat point in the sky where an extension of the North Pole intersects the celestial sphere. The North Star,
Polaris is located very near the North Celestial Pole (1, Fig. 13). The celestial equator (2, Fig. 13) is a
projection of the Earth’s equator onto the celestial sphere.
So just as an object's position on the Earth’s surface can be located by its latitude and longitude, celestial
objects may also be located using Right Ascension and Declination. For example, you could locate Los
Angeles, California, by its latitude (+34°) and longitude (118°). Similarly, you could locate the Ring Nebula(M57) by its Right Ascension (18hr) and its Declination (+33°).
• Right Ascension (R.A.): This celestial version of longitude is measured in units of hours (hr), minutes(min), and seconds (sec) on a 24-hour "clock" (similar to how Earth's time zones are determined bylongitude lines). The "zero" line was arbitrarily chosen to pass through the constellation Pegasus — a sortof cosmic Greenwich meridian. R.A. coordinates range from 0hr 0min 0sec to 23hr 59min 59sec. Thereare 24 primary lines of R.A., located at 15-degree intervals along the celestial equator. Objects locatedfurther and further East of the zero R.A. grid line (0hr 0min 0sec) carry higher R.A. coordinates.
• Declination (Dec.): This celestial version of latitude is measured in degrees, arc-minutes, and arcseconds (e.g., 15° 27' 33"). Dec. locations north of the celestial equator are indicated with a plus (+) sign
(e.g., the Dec. of the North celestial pole is +90°). Dec. locations south of the celestial equator are
indicated with a minus (–) sign (e.g., the Dec. of the South celestial pole is –90°). Any point on the celestial
equator (such as the the constellations of Orion, Virgo, and Aquarius) is said to have a Declination of zero,shown as 0° 0' 0."

Locating the Celestial Pole
To get basic bearings at an observing location, take note of where the sun rises (East) and sets (West) eachday. After the site is dark, face North by pointing your left shoulder toward the direction where the sun set.
To point at the pole, find Polaris by using the Big Dipper as a guide (Fig. 14).

Polar Alignment Procedure

1+90° Dec.

North Celestial Pole
(Vicinity of Polaris)

17
18
19

16

Star

15

20 21

14

13 12

11

22

23

0

1

Right Ascension

South Celestial Pole

10

9Earth’s
Rotation-90° Dec.

Fig. 13: The Celestial Sphere.

- 16 -

ation
clin
De

As the Earth rotates once on its axis every
24 hours, astronomical objects appear tomove across the sky in an arc. Thisapparent motion (see SIDEREAL RATE,
page 13) is not obvious to the unaided eye,but viewed through a telescope such as theETX-90EC, ETX-105EC, 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.
Foreasy
trackingofastronomical objects your ETX telescopeshould be polar aligned.

2

3

8
4

7
6
5

2

Celestial Equator
0° Dec.

LO

HI

22°
33°

23°

34°

35°
24°

There are two mounting methods available to polaralign the telescope depending on whether you use theoptional #883 Deluxe Field Tripod or a table tripod(specific to your model of ETX telescope).

Little Dipper

To polar align using the #883 Deluxe Field Tripod (Fig.
17), follow the instructions provided with the tripod. To
polar align using the #880 (ETX-90EC) or #881 Table
Tripod (ETX-105EC or ETX–125EC, Fig. 16), use thefollowing procedure.
1. Make sure the viewfinder is aligned with your ETX
telescope (see ALIGNING THE VIEWFINDER, page
10).

PolarisBig Dipper

Cassiopeia

Fig. 14: Locating Polaris.

36°

2. Remove the two hole covers (12, 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.

25°
37°

26°
38°

27°

39°

40°
28°

41°
29°
42°
30°
43°

31°
44°

32°

33°

45°

46°

34°

47°

35°

48°

Fig. 15:
Example ofStandard Tripod
Leg Latitude
Scales.

3. Determine the latitude of the observing location from a road map, atlas, or the Latitude Chart for Major
Cities of the World, page 27; determining the latitude within about one degree is sufficient.
4. Each table tripod is equipped with two adjustable tripod legs, only one of which will be used: The
standard tripod leg is used at observing latitudes as shown 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.
5. Locate the two mounting holes on the bottom of the telescope drive base. Mount the appropriate
adjustable tripod leg 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-105EC, ETX-125EC)
33.5° to 49.5° uses high-latitude hole. 23.25° to 36.5° uses alternate hole.
High-Latitude Tripod Leg (ETX-105EC, 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. Set aside the tripod leg that is not to
be used.
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 beextended. If using the standard tripod leg, extend the leg so that the center of the thumbscrew headaligns with the latitude of the observing location on the scale. Retighten the thumbscrew to a firm feel. (Ifusing the high-latitude 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 thethumbscrew is set next to the 41°
reading on the scale.
Note: With the standard tripod leg
threaded into the appropriate hole inthe drive base, the latitude scale may
be at an inconvenient position forreading (e.g., the scale faces thedrive base). This situation can be
remedied by unthreading the leg,removing the thumbscrew, rotating
the inner leg 180°, then reinserting
the thumbscrew. The scale will now
be readable when threaded back into
the telescope base.
7. Loosen the vertical and horizontal
locks (6 and 9, Fig. 1) and rotate thetelescope so that it is oriented asshown in Fig. 16. Tighten the vertical

Po
lar
is

7
8

2
5

1

Dec. at 90°

3
4

6

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.

- 17 -

CAUTION!
When using the #880 Table
Tripod with the ETX-90EC,
the optional #1422 LowLatitude Balance Weight isrecommended if thetelescope is to be polaraligned below 30°, or ifheavy accessories areattached to the eyepieceend of the telescope. The
low-latitude balance
weight is recommended
for the ETX-105EC or ETX125EC at all observing
latitudes and is included
as standard equipmentwith the #881 Table Tripod.

and horizontal locks. In thisorientation the telescope’s opticaltube is lined up parallel to the
tripod’s adjustable leg.
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 thetelescope on a firm and levelsurface 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).

ALT/AZ:
Tripod headlocked at 90°

POLAR:
Tripod headlocked at
observer’s
latitude

9. If using the high-latitude tripod leg in
the Northern hemisphere, extend Fig. 17: Examples of Alt/Az and polar mounting of an
the leg until the telescope’s polar ETX-90EC to the optional #883 Deluxe Field Tripod.
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: Observers located in the earth’s Southern Hemisphere must 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) can be affected only by (a)loosening the locks (6 and 9, Fig. 1), which permits the optical tube to be moved freely within thetelescope mounting, or (b) more generally, with the locks in their “locked” positions, by using the Arrowkeys of the Electronic Controller.
Note: For almost all astronomical observing requirements, approximate settings of thetelescope’s 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 wheremore precise polar alignment is desirable, refer to APPENDIX C, page 28.

PHOTOGRAPHY
Photography through your ETX model requires the addition of the optional #64 T-Adapter (see OPTIONALACCESSORIES, page 20). With the #64 T-Adapter attached to the telescope (Fig. 18), 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.
For through-the-telescope photography, turn the flip-mirror control (5, Fig. 18) to the “down” position,
allowing light to pass straight through the telescope and out the photo port (15, 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 thetelescope 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 thecamera lens removed).
The #64 T-Adapter consists of two sections (1 and 2, Fig. 18), which are threaded together in shipment.
You may use either of the following photographic mounting formats to couple the camera body to thetelescope’s photo port thread.
• Format 1: Camera Body + T-Mount + Section (1) of the #64 T-Adapter (7, Fig. 18).
ETX-90EC
ETX-105EC
ETX-125EC

1250mm at f/13.8
1640mm at f/15.6
1900mm at f/15

Format 1 utilizes only the short section of the #64 T-Adapter to permit close-coupling of a camera body tothe telescope. In this format vignetting will occur: the photographic image will appear on film with a slightdarkening at the corners of the 35mm frame (see Fig. 19).
• Format 2: Camera Body + T-Mount + Sections (1) and (2) of the #64 T-Adapter (see Fig. 18).
ETX-90EC
ETX-105EC
ETX-125EC

1450mm at f/16
1830mm at f/17.42310mm at f/18

- 18 -

Format 2 utilizes both sections of the#64 T-Adapter threaded together toform a rigid unit. In this configuration
there is no field vignetting: images are
illuminated to the edges of a standard
35mm frame (see Fig. 20).
To frame an object in the viewfinder ofthe 35mm camera body, slightly
loosen the knurled attachment ring (3,Fig. 18), which threads the #64 TAdapter to the telescope’s photo port;
rotate the camera body to achieve
proper framing of the object; then retighten the knurled ring.

2

1

7

3
6

4

5

Fig. 18: Example of photography through the ETX using the
Photography through a long lens, such #64 T-Adapter: (1) Short section of #64 T-Adapter;as the ETX, requires special technique (2) Extension section of #64 T-Adapter; (3) Knurled attachment
for good results. The photographer ring; (4) T-mount; (5) Flip-mirror control in “down” position; (6)should expect to use a roll or two of 35mm camera body; (7) Format 1.
film in acquiring this technique. Longlens photography has its own rewards, however, which short-focus lenses cannot duplicate.
A Few Tips on Photography
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), 1640mm to 1830mm(ETX-105EC), or 1900mm to 2310mm (ETX–125EC), even small external vibrations can easily ruin anotherwise good photo.
CAUTION: With the #64 T-Adapter and a camera body mounted to the ETX photo port, thetelescope can be rotated vertically only 45°. Moving past this point may damage the telescopeand camera.
2. Use a cable-operated shutter release. Touching the camera body to operate the shutter will almost
certainly introduce undesirable vibrations.
Fig. 19: Example of aformat 1 photo.

3. Focus the image with extreme care. While observing the subject through the camera’s reflex viewfinder,
turn the ETX's focus knob (8, 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 longtelephoto 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 thebest way to determine proper shutter speed in any given application.

Fig. 20: Example of aformat 2 photo.

Note: The camera used with an 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 tocompensate for a dark sky.
5. Terrestrial photography through an 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 hadtime to build up heat.
6. Photography of the Moon and planets through an ETX model can be especially gratifying, but points
1 through 4 should be particularly noted in this case. Lunar or planetary photography requires that thetelescope be polar aligned (see POLAR ALIGNMENT PROCEDURE, page 16), and that the telescope’s
motor drive be in operation (see APPENDIX A, page 26).
Note: Long-exposure photography of deep-sky objects is not practical with an ETX model, since
this type of photography requires special electronic and optical guiding devices not available forthis telescope.

- 19 -OPTIONAL ACCESSORIES
A wide assortment of professional Meade accessories are available for the for ETX telescopes. Meade
accessories greatly extend many important applications to the telescope, from low-power, wide-fieldterrestrial 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 atmore than 3,000 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 thepast 25 years, the Meade #497 Autostar Computer Controller (Fig. 21) turns your ETX model into an
automatic celestial object locating system. Just plug Autostar into the telescope’s HBX port in place of thestandard-equipment Electronic Controller, do a quick telescope alignment, and you are ready to observe
any object in the Autostar’s 14,000-object database.
Fig. 21: #497
Autostar Computer
Controller.

Best of all, the Meade Autostar is easy to use. Even the most novice observer will locate dozens offascinating celestial objects the very first night out — from commonly observed objects, such as the rings ofSaturn, 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; tovery obscure objects near the telescope’s threshold of visibility, such as spiral galaxy NGC 3310 in Ursa
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.

Fig. 22: AstroFinder
software.

AstroFinder Software/#505 Cable Connector Kit: With Meade AstroFinder software (Fig. 22) loaded
into your PC, Autostar-equipped ETX–90EC, ETX-105EC, and ETX-125EC telescopes may be remotely
controlled from the PC display. The #505 Cable Connector Set, permitting connection of ETX, Autostar,and PC, is included with each AstroFinder package.
Eyepieces: For higher and lower magnifications, Meade Super Plössl (SP) and Super Wide Angle (SWA)
eyepieces (Fig. 23), as well as the Series 4000 8mm to 24mm Zoom eyepiece, yield high-resolution imaging
with all ETX telescope models. A useful selection includes the SP 9.7mm, SP 12.4mm, and SWA 18mm.
Under good seeing conditions, Meade Ultra Wide Angle 4.7mm and 6.7mm eyepieces present the widest
obtainable fields of view at high powers and are well suited for observing the Moon and planets. Alternative
optional eyepieces may be chosen from the Meade Series 3000 Plössl eyepieces. Powers obtained witheach eyepiece are shown in the following table.

Eyepiece
Fig. 23: Optional
Eyepieces yield higher
and lower magnifying
powers.

SP 6.4mm
SP 9.7mm
SP 12.4mm
SP 15mm
SP 20mm
SP 26mm *SP 32mm
SP 40mm

ETX-90EC
Power 2x Barlow

ETX-105EC
ETX-125EC
Power 2x Barlow Power 2x Barlow

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

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

230
152
119
98
74
57
46
37

459
303
237
196
147
113
92
74

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

107
82
60

213
163
120

138X
106X
78X

275X
211X
155X

UWA 4.7mm
UWA 6.7mm

266X
187X

N/A
374X **

313
219

N/A
439**

404X
284X

N/A
567X*** Included as standard-equipment with the ETX models.
** Use these eyepieces only under extremely steady atmospheric conditions.
Fig. 24: Use the#126 2x Barlow Lens
to double themagnification of theeyepiece employed.

#126 2x Barlow Lens: An amplifying lens, the multi-coated #126 2x Barlow (Fig. 24) doubles the power ofall eyepieces with which it is used. Insert the #126 into the telescope’s eyepiece holder first, followed by aneyepiece. Example: By itself, the SP 26mm eyepiece yields a power of 73X with the ETX-125EC; whenused with the #126 2x Barlow Lens, this eyepiece yields 146X.

- 20 -

#825 8 x 25mm Right-Angle Viewfinder: Included as standard-equipment on ETX-105EC and ETX-125EC
models, the 8 x 25mm Right-Angle Viewfinder (Fig. 25) 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 viewfinder’s wide-angle 7.5° actual field facilitates object location. Precise
focusing of the image is accomplished with a helicoid mechanism.

Fig. 25: #825 RightAngle Viewfinder.

#64 T-Adapter: The basic means of photography through any ETX Astro telescope, the #64 T-Adapter
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 effectbecomes the camera's lens (see PHOTOGRAPHY, page 18).
#932 45° Erecting Prism: All ETX models include an internal optically-flat mirror to reflect light to thetelescope’s 90° astronomical observing position. In this position the telescope’s image is upright, butreversed. For terrestrial observing with an ETX model, the #932 Erecting Prism (Fig. 26) results in a fully
correctly oriented image and a convenient 45° observing angle.

Fig. 26: The #932 45°
Erecting Prism.

#774 Hard Carrying Case (for the ETX-90EC), #776 Hard Carrying Case (for the ETX-105EC), and #775
Hard Carrying Case (for the ETX-125EC): For secure portability of ETX Astro Telescope models in the field,
Meade hard carrying cases (Fig. 27) are fully lined with fitted foam inserts. They accept the complete ETX
Astro Telescope plus optional accessories.
#765 Soft Carry Bag: The Meade soft-padded carry bag (Fig. 28) is well suited to travel with the ETX-90EC
Astro Telescope. Each carry bag includes a shoulder strap and permits ready transport of the complete
telescope, including accessories.
Power Adapters and Cords: In addition to their internal battery packs, ETX-90EC, ETX-105EC, and ETX125EC 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, an ETX telescope may be powered in the fieldfrom an automobile cigarette lighter plug by using the #607 Power Cord, a 25-ft. cord that plugs into thetelescope’s control panel and supplies 12vDC directly from the car battery.
#1244 Electric Focuser (for the ETX-90EC and ETX-105EC) and #1247 Electric Focuser (ETX-125EC):
Meade-engineered for smooth, rapid focusing with any ETX model, each electric focuser (Fig. 29) includes
coarse and micro-fine speeds. The standard-equipment hand controller accepts one (user-supplied) 9-volt
battery and focuses the ETX telescope. On the ETX models, the focuser plugs into, and is powered by, thetelescope’s control panel, with operation effected through either the Electronic Controller or the optional#497 Autostar Computer Controller.
#880 Table Tripod (for ETX-90EC) and #881 Table Tripod (for ETX-105EC and the ETX-125EC): ETX90EC, ETX-105EC, and ETX-125EC models permit pushbutton tracking of astronomical objects from theirstandard-equipment Electronic Controllers. For fully automatic tracking, a table tripod (Fig. 16), or the #883
Deluxe Field Tripod, may be added allowing for polar alignment of the telescope.

Fig. 30a: 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.

Each table tripod includes two fixed legs and two variable-length legs inscribed with a range of latitudesettings for quick polar alignment. At observing latitudes below about 25°, the optional #1422 Low-Latitude
Balance Weight (8, Fig. 16) is recommended for ETX-90 Astro Telescope models; the low-latitude balance
weight is included with the table tripod for the ETX-105EC and the ETX-125EC Astro Telescopes.
#883 Deluxe Field Tripod: Provides a rigid mounting platform for the ETX-90EC, ETX-105EC, and ETX125EC Astro Telescope models. The #883 tripod includes micrometric controls for precise equatorialalignment of the telescope at any observing latitude from 20° to 90°. The ETX telescope may be mounted
in the altazimuth orientation (Fig. 30a) for terrestrial viewing or in the equatorial (or polar) mode (Fig. 30b)
for automatic tracking of astronomical objects.
#887 Advanced Field Tripod for the ETX-105EC or ETX-125EC: For extra stability in sensitive
applications of the ETX-105EC or the ETX-125EC even at the highest magnifications, the fixed height #887
Tripod permits either altazimuth or equatorial orientation of the telescope for astronomical or terrestrial
observing. The #887 includes an equatorial wedge for polar alignment. The tripod's 2"-diameter steel legs
collapse for easy transport in the field.

Fig. 30b: The #883
Deluxe Field Tripod
shown with tripod headtilted for polar alignment.

Fig. 27: #774 Hard
Carrying Case shown withan ETX-90EC.

Fig. 28: The #765 Soft
Carry Bag for the ETX90EC.

- 21 -

Fig. 29: #1244 Electric
Focuser.

GENERAL MAINTENANCE
Your ETX model telescope is a precision optical instruments designed to yield a lifetime of rewarding
observations. Given the care and respect due any precision instrument, the telescope 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 lenscauses 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 lenscleaner.
3. You may remove organic materials (e.g., fingerprints) from the front lens with a solution of 3 parts distilledwater to 1 part isopropyl alcohol. A single drop of biodegradable dishwashing soap may be added perpint 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, atissue, 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 cellthroughout 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 factory.
5. If your 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 isrecommended 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 inwarm 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 your 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 9).
7. The super-gloss anodized finish of any ETX model’s deep-violet optical tube fades if left in direct sunlightfor prolonged periods.
8. Do not leave your ETX model outdoors on a warm day or inside a sealed car for an extended period oftime; 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 ETX models. These wrenches are used asfollows:• Small wrench (.05”): Use the small wrench to tighten the set-screws 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 rearcell.

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 (6and 9, 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 candamage the optical tube and/or the objective lens, and knock the optics out of alignment. It is highly
recommended to use an optional carry case to transport the telescope (see OPTIONAL ACCESSORIES,
page 21).

- 22 -

Inspecting the Optics
A Note About the “Flashlight Test:" If a flashlight or other high-intensity 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, ETX-105EC, and ETX-125EC.

The power indicator light on the telescope does not come on or there is no responsewhen pressing the Electronic Controller Arrow keys:• Verify that the Computer Control panel power switch (10A, Fig. 1) is in the ON position.
• Verify that the Electronic Controller cord (4, Fig. 3) is firmly connected to the HBX port (10C, Fig. 1).
• If using internal power (batteries), verify that the batteries are installed correctly and that they havesufficient charge (see ASSEMBLY INSTRUCTIONS, page 9).
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(10D, Fig. 1) 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 backto 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.

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 (14, 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 flip-mirror control is in the “down”
position if using the #932 Erecting Prism or doing photography with an ETX model (see TELESCOPECONTROLS, page 6 and PHOTOGRAPHY, page 18).

Object appears in the viewfinder but not in the eyepiece:• The viewfinder is not properly aligned with the telescope (see ALIGNING THE VIEWFINDER, page 10).

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 APPENDIX A, page 26).
• The battery power may be low (see ASSEMBLY INSTRUCTIONS, page 9).

Telescope does not track a celestial object:• The telescope tracks celestial objects automatically only if it is placed in the polar mode (see APPENDIX A,
page 26) and the telescope is polar aligned (see POLAR ALIGNMENT, page 16) using the #880 (ETX-90EC),#881 (ETX-105EC or ETX-125EC) Table Tripod, or #883 Deluxe Field Tripod (see OPTIONAL ACCESSORIES,
page 21). 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 Arrow keys on
the Electronic Controller. Automatic tracking of objects in the Alt/Az mode requires the optional #497 Autostar
Computer Controller. Also the Horizontal and Vertical locks must be locked (page 6).

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 (seeUNDERSTANDING MAGNIFICATION, page 12).

- 23 -

• 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 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 12).
• For clear viewing of objects, turn the focus knob (8, Fig. 1) slowly since the “in-focus” point of a telescopeis 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 CHANGING MODES, page 26).
• Verify that the vertical and horizontal locks are tight (see TELESCOPE CONTROLS, page 8).

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

Telescope pauses when changing slew direction:• This pause is normal (see ARROW KEYS, page 8).

A terrestrial object appears reversed left-for-right:• An eyepiece in the standard 90° observing position (4, Fig. 1) reverses an object left-for-right: To view acorrectly oriented image requires the optional #932 Erecting Prism (see OPTIONAL ACCESSORIES, page
21).

Meade Customer Service
If you have a question concerning your ETX model, call the Meade Instruments Customer Service
Department at (949) 451-1450, or fax to (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 thetelescope to the factory.

- 24 -

Slow-Motion Controls . . . . . . . . . electric, 4 speed, both axes
Optional Autostar Capability . . . . . . . . . . . . . . . . . . . . . . . yes
Hemispheres of operation . . . . . North and South, switchable
Bearings:
Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . ball bearings
Azimuth . . . . PTFE thrust bearing and radial ball bearing
Materials:
Tube body . . . . . . . . . . . . . . . . . . . . . . . . . . . aluminum
Mounting . . . . . . ABS, with internal aluminum structurePrimary mirror . . . . . . . . . . . . . . . . . . . . . . Pyrex® glass
Correcting lens. . . . . . . . . . . BK7 optical glass, Grade-A

Specifications: ETX-90EC 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

Telescope dimensions:. . . . . . . . . . . . . 43cm x 25cm x 20cm (17” x 10” x 8”)
Telescope net weight:(incl. Electronic Controller & batteries) . . 6.1kg (13.5 lbs)
Telescope shipping weight . . . . . . . . . . . . . . . 8.3kg (18.4 lbs)
Battery Life (approx.):with Electronic Controller . . . . . . . . . . . . . . . . . . . 45 hrs
with Autostar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 hrs

Specifications: ETX-125EC Astro Telescope

Motor Drive System DC servo 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

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 . . DC servo 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . ball bearings
Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . ball bearings
Materials:
Tube body . . . . . . . . . . . . . . . . . . . . . . . . . . . aluminum
Mounting . . . . . . . ABS, with internal aluminum structurePrimary mirror . . . . . . . . . . . . . . . . . . . . . . Pyrex® glass
Correcting lens. . . . . . . . . . . BK7 optical glass, Grade-A

Specifications: ETX-105EC Astro Telescope
Optical design . . . . . . . . . . . . . . . . . . . Maksutov-Cassegrain
Primary mirror diameter . . . . . . . . . . . . . . . . . 116mm (4.56”)
Clear aperture . . . . . . . . . . . . . . . . . . . . . . . . 105mm (4.13”)
Focal length . . . . . . . . . . . . . . . . . . . . . . . . . 1470mm (57.8”)
Focal ratio (photographic speed) . . . . . . . . . . . . . . . . . . . f/14
Near focus (approx). . . . . . . . . . . . . . . . . . . . . . . 4.6m (15 ft)
Resolving power . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 arc secs
Super multi-coatings (EMC) . . . . . . . . . . . . . . . . . . . standard
Limiting visual stellar magnitude (approx.). . . . . . . . . . . . 12.1
Image scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.99°/inch
Maximum practical visual power. . . . . . . . . . . . . . . . . . . 420x
Optical tube dimensions(dia. x length) . . . . . . . . 12.4cm x 32.8cm (4.88” x 12.9”)
Eyepiece . . . . . . . . . . . . . . . . . . . . . . . . . Super Plössl 26mm
Viewfinder. . . . . . . . . . . . . . . . . . . . . . . 8 x 25mm right-angle
Secondary mirror obstruction (dia.; %). . . 3.3cm (1.32”); 9.4%
Telescope mounting . . . . . . . . . . . . . . . fork type; double tine
Setting circle diameters . . . . . . . . . . . . . Dec.: 3.81”; RA: 7.8”
Input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 volts DC
Motor Drive System . . DC servo motors with encoders, both axes

Telescope dimensions:. . . . . . . . . . 48cm x 23cm x 27cm (19” x 8.9” x 10.8”)
Telescope net weight:(incl. Electronic Controller & batteries) . . 6.9kg (15.2 lbs)
Telescope shipping weight . . . . . . . . . . . . . . 11.4kg (25.2 lbs)
Battery Life (approx.):with Electronic Controller . . . . . . . . . . . . . . . . . . . 45 hrs
with Autostar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 hrs- 25 -

Appendix A: ADVANCED ELECTRONIC CONTROLLER FUNCTIONS
Tracking Motor Speeds
In the polar mode the Electronic Controller normally tracks objects at the sidereal rate (see SIDEREAL RATE, page13). 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.
3) are sufficient to move the telescope slightly as the object very slowly moves off-center through the eyepiece field.
To change the tracking rate, for extended observations of an object not moving at the sidereal rate, follow theprocedure for the appropriate hemisphere:

Northern Hemisphere Polar:
1.
2.
3.

Step 2.

Step 4.

Press and hold the MODE key (5, Fig. 3) 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 the SPEED key (3, Fig. 3) 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 IN key (7, Fig. 3) and light 4 comes on steady. The tracking rate is now 0.5% faster than sidereal.
If the object you're tracking is moving faster than the sidereal rate, look through the eyepiece and continue topress the IN key until the object remains centered with little or no drifting in the eyepiece.
Note: The tracking rate can be increased by up to 65% (127 presses of the IN key).

4.

To use a rate slower than sidereal, press the OUT (6, Fig. 3) 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. If the object
you're tracking is moving slower than the sidereal rate, look through the eyepiece and continue to press the
OUT key until the object remains centered with little or no drifting in the eyepiece.

5.

Press and hold the MODE key until only a single light is on. This exits the Mode function. If Northern orSouthern Hemisphere polar mode was chosen, the motor drive starts operating at the sidereal rate.
Use the four Arrow keys (1, Fig. 3) to slew the telescope to the desired object. To change the slew speed,press the SPEED key.

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

Step 3.

Step 5.

6.

Southern Hemisphere Polar:
1.
2.
3.

Step 2.

Press and hold the MODE key (5, Fig. 3) 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. 3) until lights 1 and 2 are on steady, light 3 is off, and Light 4 is blinking.
Press the IN key (7, Fig. 3) and light 4 comes on steady. The tracking rate is now 0.5% faster than sidereal.
If the object you're tracking is moving faster than the sidereal rate, look through the eyepiece and continue topress the IN key until the object remains centered with little or no drifting in the eyepiece.
Note: The tracking rate can be increased by up to 65% (127 presses of the IN key).

Step 4.
4.

To use a rate slower than sidereal, press the OUT key (6, Fig. 3) 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. If the object
you're tracking is moving slower than the sidereal rate, look through the eyepiece and continue to press the
OUT key until the object remains centered with little or no drifting in the eyepiece.

5.

Press and hold the MODE key until only a single light is on. This exits the Mode function. If Northern orSouthern Hemisphere polar mode was chosen, the motor drive starts operating at the sidereal rate.
Use the four Arrow keys (1, Fig. 3) to slew the telescope to the desired object. To change the slew speed,press the SPEED key.

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

Step 3.

Step 5.

6.

Changing Modes Using the Electronic Controller
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.
2.
Step 3.

Step 4.

3.
4.
5.
6.
7.

Step 5.

Step 6.

Step 8.

8.
9.

Complete the POLAR ALIGNMENT PROCEDURE on page 16.
Complete steps 2 through 8 as described in TO MOVE THE TELESCOPE USING THE ELECTRONIC CONTROLLER,
page 15, to initialize the Electronic Controller.
Press and hold the MODE key (5, Fig. 3) until lights 1 and 2 are on steady and lights 3 and 4 start blinking.
Press the SPEED key (3, Fig. 3) 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 Northernhemisphere, with the motor drive set to operate at the sidereal rate.
Press the SPEED key 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 MODE key until just one light is on. This exits the Mode function. If you choose Northernor Southern Hemisphere polar mode, the motor drive starts operating at the sidereal rate.
Use the four Arrow keys (1, Fig. 3) to slew the telescope to the desired object. To change the slew speed,press the SPEED key.

- 26 -

Appendix B: HELPFUL CHARTS
Latitude Chart for Major Cities of the WorldStar LocatorTo aid in the polar alignment procedure (see page 16), 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 whenthese stars are prominent in the night sky. This list will aid theobserver to find alignment stars at various times of the year.
For example, if it is a midsummer evening in the Northernhemisphere, Deneb in the constellation Cygnus, would be an
excellent alignment star, while Betelgeuse could not be usedbecause 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 (110 km) north of the listed city, subtract one degree forevery 70 miles. If the site is over 70 miles South of the listed
city, add one degree per 70 miles.
NORTH AMERICA

SeasonStar Name

Constellation

R.A.

SpringSpringSpringArcturus
Regulus
Spica

BoötesLeo
Virgo

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

18h37m20h41m
19h51m16h30mCity

State/Prov./Country Latitude

AlbuquerqueAnchorage
Atlanta
BostonCalgary
ChicagoCleveland
DallasDenverDetroitHonolulu
JacksonKansas City
KenoshaLas Vegas
Little RockLos Angeles
Mexico City
Miami
Minneapolis
Nashville
New Orleans
New York
Oklahoma City
OttawaPhiladelphia
Phoenix
PortlandSalt Lake CitySan Antonio
San Diego
San Francisco
SeattleWashington
EUROPE

New Mexico
AlaskaGeorgia
Massachusetts
Alberta
Illinois
Ohio
Texas
Colorado
Michigan
Hawaii
Mississippi
Missouri
Wisconsin
NevadaArkansas
California
MexicoFloridaMinnesota
Tennessee
Louisiana
New York
Oklahoma
Ontario
Pennsylvania
Arizona
OregonUtah
Texas
California
California
Washington
District of Columbia

35° N
61° N
34° N
42° N
51° N
42° N
41° N
33° N
40° N
42° N
21° N
32° N
39° N
45° N
36° N
35° N
34° N
19° N
26° N
45° N
36° N
30° N
41° N
35° N
45° N
40° N
33° N
46° N
41° N
29° N
33° N
38° N
47° N
39° N

SummerSummerSummerSummerVega
Deneb
AltairAntares

Lyra
CygnusAquilaScorpius

Fall
Fall
Fall

Markab
Fomalhaut
Mira

Pegasus23h05m 15° 12"
Piscis Austrinus 22h58m -29° 38"
Cetus
02h19m -02° 58"

Winter
Winter
Winter
WinterRigel
Betelgeuse
SiriusAldebaran

Orion
Orion
Canis Major
TaurusCity

Country

LatitudeAmsterdam
AthensBern
Copenhagen
DublinFrankfurt
Glasgow
Helsinki
LisbonLondonMadrid
Oslo
Paris
Rome
Stockholm
ViennaWarsaw

Netherlands
GreeceSwitzerland
Denmark
IrelandGermany
ScotlandFinland
Portugal
EnglandSpain
NorwayFrance
Italy
SwedenAustria
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

05h15m05h55m06h45m04h35m38° 47"45° 17"08° 52"-26° 26"-08° 12"07° 25"-16° 43"16° 31"

SOUTH AMERICA

City

Country

Latitude

Bogotá
São Paulo
Buenos Aires
Montevideo
Santiago
CaracasASIA

Colombia
BrazilArgentina
Uruguay
Chile
Venezuela

4° N
23° S
35° S
35° S
34° S
10° N

City

Country

LatitudeBeijingHong Kong
Seoul
TaipeiTokyo
SapporoBombayCalcutta
Hanoi
Jedda
AFRICA

China
China
South Korea
Taiwan
Japan
Japan
India
India
Vietnam
Saudi Arabia

40° N
23° N
37° N
25° N
36° N
43° N
19° N
22° N
21° N
21° N

City

Country

Latitude

Cairo
Egypt
Cape Town
South Africa
Rabat
Morocco
Tunis
Tunisia
Windhoek
Namibia
AUSTRALIA AND OCEANIA

30° N
34° S
34° N
37° N
23° S

City

State/Country

Latitude

Adelaide
Brisbane
Canberra
Alice Springs
HobartPerthSydneyMelbourne
AucklandSouth Australia
Queensland
New South Wales
Northern Territory
Tasmania
Western Australia
New South Wales
Victoria
New Zealand

35° S
27° S
35° S
24° S
43° S
32° S
34° S
38° S
37° S

Appendix C: PRECISE POLAR ALIGNMENT; SETTING CIRCLES
If desired, you may obtain more precise polar alignment by first accomplishing basic polar alignment asdetailed in POLAR ALIGNMENT PROCEDURE, page 16, then returning to this procedure:
Important Note:
For almost all
astronomical
observingrequirements,
approximate settingsof the telescope’s
latitude and polar axis
are acceptable. Do
not allow undue
attention to precise
polar alignment of thetelescope to interferewith your enjoymentof the instrument.

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 polaralignment will be lost.
1. Orient the entire telescope, including tripod or tripod legs, so that the polar axis is pointing toward Polaris(Fig. 14).
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 theadjustable 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 makethe alignment more precise.
Although the above procedure is somewhat tedious (since the field of view of the telescope with the SP
26mm eyepiece is only about 1°), it is a worthwhile effort if precise polar alignment is desired (e.g., ifphotography 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 the ETX models, it is recommended topurchase the #883 Deluxe Field Tripod. The tripod head tilts easily to the local latitude angle for quick polaralignment, and it locks in a 90° position to facilitate Alt/Az viewing (see OPTIONAL ACCESSORIES, page 20).

Setting Circles
40
30

40

20

10

0

10

20

30

The ETX models are equipped with R.A. and Dec. setting circles (13 and 16, Fig. 1) to aid in locating faintcelestial objects when the telescope has been polar aligned. Setting circles emulate the celestialcoordinates 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 an ETX model polar aligned, use the Electronic Controller Arrow keys (1, Fig. 3) to move the telescopein R.A. (left and right keys) and Dec. (up and down keys).

Fig. 31: Section of
Declination setting circle.

Note: The Dec. setting circle is located on the left arm of the telescope fork mount. The rightarm of the mount contains a graduated circle (mounted behind the knurled knob of the verticallock), without Dec. numbers.
• Declination Setting Circle: The Dec. setting circle (Fig. 31) has been factory set to read the correct
Declination of celestial objects.

12
12

11
13

10
14

Fig. 32: Section of Right
Ascension 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 smoothknob covering the Dec. setting circle until the setting circle moves freely. Reposition the setting circle sothat the 0 setting aligns with the Dec. pointer (5, Fig. 16). Retighten the Dec. knob.
• Right Ascension Setting Circle: Since celestial objects move in R.A., the R.A. setting circle (Fig. 32)
must be reset as each object is located during an observing session. The R.A. pointer is located on thedrive base 90° counterclockwise from the telescope’s Computer Control panel (10, Fig. 1) immediately
under the R.A. circle.

Note: The R.A. circle
has two rows ofnumbers from 0 to 23,
corresponding to thehours of a 24-hourclock. The upper row
of numbers is used byobservers in the
Earth’s Northern
Hemisphere, thelower row by
observers in the
Earth’s Southern
Hemisphere.

To use the setting circles to find astronomical objects, the ETX must first be polar aligned. It is advisablethat the motor drive be turned on (see APPENDIX A, page 26) and that a low-power 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 bright stars are listed in the STAR
LOCATOR, page 27, astronomy magazines, text books, or star charts. Center this object in the telescope’s
field of view.
2. Manually turn the R.A. circle (13, 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 thetelescope using the Electronic Controller Arrow keys) so that the R.A. and Dec. pointers read thecoordinates of the second object.
5. If the above procedure has been followed carefully, the second object will now be in the telescope’s fieldof 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 thecoordinates of the second object. Otherwise the second object will no longer be in the positionindicated by the R.A. circle.
Using setting circles requires a developed technique. When using the circles for the first time, try hoppingfrom one bright star (the calibration star) to another bright star of known coordinates. Practice moving thetelescope from one easy-to-find object to another. In this way the precision required for accurate object
location becomes familiar.

- 28 -

Appendix D: YOU AND THE UNIVERSEOBJECTS IN SPACEIn the early 17th century, Italian Scientist Galileo, using a crude telescope considerably smaller than the
ETX-90EC, turned it to look towards the sky instead of distant trees and mountains. What he saw, and what
he realized about what he saw, forever changed the way mankind thinks of the universe. Imagine what it
must have been like being the first human to see moons revolve around the planet Jupiter or to see thechanging phases of Venus! Because of his observations, Galileo correctly realized Earth's movement andposition around the Sun, and in doing so, gave birth to modern astronomy. Yet Galileo's telescope was so
crude, he could not clearly make out the rings of Saturn.
Galileo's discoveries laid the foundation for understanding the motion and nature of the planets, stars, andgalaxies. Building on his foundation, Henrietta Leavitt determined how to measure the distance to stars;
Edwin Hubble proposed a glimpse into the origin of the universe; Albert Einstein unraveled the relationshipof time and light; and 21st-century astronomers are currently discovering planets around stars outside oursolar system. Almost daily, using sophisticated successors to Galileo's crude telescope, such as the Hubble
Space Telescope and the Chandra X-ray telescope, more and more mysteries of the universe are being
solved and understood. We are living in the golden age of astronomy.
Unlike other sciences, astronomy welcomes contributions from amateurs. Much of the knowledge we haveon subjects such as comets, meteor showers, variable stars, the Moon, and our solar system comes fromobservations made by amateur astronomers. So as you look through your Meade ETX telescope, keep inmind Galileo. To him, a telescope was not merely a machine made of glass and metal, but something far
more—a window through which the beating heart of the universe might be observed.

Autostar Glossary
If you're using the optional #497 Autostar handbox, be sure to make use of Autostar’s Glossary feature. The
Glossary menu provides an alphabetical listing of definitions and descriptions of common astronomicalterms. Access directly through the Glossary menu or through hypertext words embedded in Autostar. See
the Autostar manual for more information.
Listed below are some of the many astronomical objects that can be seen with your ETX telescope.

The Moon
The Moon is, on average, a distance of 239,000 miles (380,000km) from Earth and is best observed during
its crescent or half phase when Sunlight strikes the Moon’s surface at an angle. It casts shadows and adds
a sense of depth to the view (Fig. 33). No shadows are seen during a full Moon, causing the overly brightMoon to appear flat and rather uninteresting through the telescope. Be sure to use a neutral Moon filter
when observing the Moon. Not only does it protect your eyes from the bright glare of the Moon, but it also
helps enhance contrast, providing a more dramatic image.

Fig. 33: The Moon.
Note the deep
shadows in the craters.

Using your ETX model, brilliant detail can be observed on the Moon, including hundreds of lunar craters andmaria, described below.
Craters are round meteor impact sites covering most of the Moon’s surface. With no atmosphere on theMoon, 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 areancient impact basins that were filled with lava from the interior of the Moon by the depth and force of themeteor or comet impact.
12 Apollo astronauts left their bootprints on the Moon in the late 1960’s and early 1970’s. However, notelescope 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.
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 the
MEADE GENERAL CATALOG for more information).

Planets
Planets change positions in the sky as they orbit around the Sun. To locate the planets on a given day ormonth, consult a monthly astronomy magazine, such as Sky and Telescope or Astronomy. Listed below are
the best planets for viewing through your ETX model telescope.
Venus is about nine-tenths the diameter of Earth. As Venus orbits the Sun, observers can see it go throughphases (crescent, half, and full) much like those of the Moon. The disk of Venus appears white, as sunlightis 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.

- 29 -

Fig. 34: Jupiter andits four largest
moons. The moons
can be observed ina different position
every night.

Fig. 35: Saturn has
the most extensive
ring structure in our
Solar System.

Jupiter (Fig. 34) is the largest planet in oursolar system, with a diameter 11 times that ofEarth. Jupiter appears as a disk with dark lines
stretching across the surface. These lines arecloud bands in the atmosphere. Four of
Jupiter’s 29 (and still counting!) moons (Io,Europa, Ganymede, and Callisto) can be seen
as star-like points of light when you use eventhe lowest magnification. The number of moons
visible on any given night changes as they
circle around the giant planet.
Saturn (Fig. 35) is nine times the diameter ofEarth and appears as a small, round disk withrings extending out from either side. In 1610,
Galileo, the first person to observe Saturnthrough a telescope, did not understand thatwhat he was seeing were rings. Instead, hebelieved that Saturn had “ears.” Saturn’s rings
are composed of billions of ice particles. The
major division in Saturn's rings, called theCassini Division, is generally visible through all
three ETX models. Titan, the largest of Saturn’s
moons, can also be seen as a bright, star-likeobject 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:
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.
Nebulae are vast interstellar clouds of gas anddust where stars are formed. Most impressiveof 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.
Open Clusters are loose groupings of youngstars, all recently formed from the same diffuse
nebula. The Pleiades (Fig. 36) is an open
cluster 410 light years from Earth. Several
hundred stars of the cluster are visible throughthe your telescope.

Fig. 36: The
Pleiades is one of
the most beautiful
open clusters.

Constellations are large, imaginary patterns ofstars believed by ancient civilizations to be thecelestial equivalent of objects, animals, people,
or gods. These patterns are too large to be
seen through a telescope. To learn theconstellations, start with an easy grouping ofstars, such as the Big Dipper in Ursa Major.
Then use a star chart to explore across the sky.
Galaxies are large assemblies of stars,
nebulae, and star clusters that are bound by
gravity. The most common shape is spiral (suchas our own Milky Way), but galaxies can also
be elliptical, or even irregular blobs. The
Andromeda Galaxy (M31) is the closest spiraltype galaxy to our own. This galaxy appears
fuzzy and cigar-shaped. It is 2.2 million lightyears away in the constellation Andromeda.
- 30 -

TIPS FOR BEGINNERS
Further Study....
This manual gives only the briefest introduction toastronomy. If you are interested in pursuing further
studies in astronomy, a few topics are suggested
below that are worth reading up on. Try looking up
some of these in the optional Autostar glossary.
Also included below is a small sampling of books,
magazines, and organizations that you might findhelpful.
Topics1.

How is a star born? How does a solar systemform?
2. How is the distance to a star measured? Whatis a light year? What is red shift and blue shift?
3. How are the craters on our Moon formed? How
old is the Moon and Earth? How old is the Sun?
4. What is a black hole? A neutron star?
5. What are stars made of? Why are stars
different colors? What is a white dwarf? A red
giant? Have we ever seen the surface of a starbesides our own sun?
6. What is a nova? A supernova?
7. What are comets? Minor planets? Meteors?
Meteor showers? Where do they come from?
8. What is a planetary nebula? A globular cluster?
9. What is the Big Bang? Is the universe
expanding or contracting, or does it always
remain the same? What is dark matter?
10. What is an extrasolar planet? What is anaccretion (or protoplanetary) disk?
11. What is the difference between an elliptical, aspiral, and an irregular galaxy?
Books
1.

The Guide to Amateur Astronomy by Jack
Newton and Philip Teece

2.

The Sky: A User’s Guide by David Levy

3.

Turn Left at Orion by Guy Consolmagno & Dan
Davis

4.

Astrophotography for the Amateur by Michael
Covington

Magazines
1.
2.

Sky & TelescopeBox 9111, Belmont, MA 02178
Astronomy
Box 1612, Waukesha, WI 53187

Organizations:
1.

2.
3.

Astronomical League
Executive Secretary
5675 Real del Norte, Las Cruces, NM 88012
The Astronomical Society of the Pacific
390 Ashton Ave, San Francisco, CA 94112
The Planetary Society
65 North Catalina Ave, Pasadena, CA 91106

And watch Jack Horkheimer, Star Gazer, on yourlocal PBS station.

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