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Meade ETX-90EC Astro Telescope Instruction Manual
WARNING! Never use the Meade ETX-90EC Astro Telescope to look at the Sun! Looking at or near the Sun will cause instant and irreversible damage to your eye. Eye damage is often painless, so there is no warning to the observer that damage has occurred until it is too late. Do not point the telescope or its viewfinder at or near the Sun. Do not look through the telescope or its viewfinder as it is moving. Children should always have adult supervision while observing.
A wide assortment of professional Meade accessories is available for the ETX-90EC. Meade accessories greatly extend many important applications to the telescope, from low-power, wide-field terrestrial viewing to high-power lunar and planetary observing. The premium quality of these accessories is well-suited to the quality of the instrument itself.

Meade telescopes and accessories, including optional accessories for ETX-series telescopes are available at more than 2000 dealer locations in the U.S. and Canada and through Meade international distributors worldwide.

ETX Astro
Fig. 22 #497 Autostar Computer Controller.
#497 Autostar Computer Controller: The #497 Autostar provides automatic GO TO capability to any of more than 14,000 objects, including deep-sky objects (galaxies, diffuse nebulae, planetary nebulae, star clusters - the best objects from the IC, NGC, and Caldwell catalogs, as well as all 110 Messier objects); 900 stars (double stars, variable stars, SAO stars); the 8 major planets from Mercury to Pluto; 26 of the brightest asteroids; 15 periodic comets; 50 earth-orbiting satellites; plus user-defined objects; and the centroids of all 88 constellations. The #497 Autostar plugs into the telescope control panel in place of the standard-equipment Electronic Controller and features a lightweight ergonomic design that is easily adaptable for both novice and advanced telescope users. Also available for the #497 Autostar is the #505 Connector Cable Set. Two cables are included. The first cable connects between the #497 Autostar and a personal computer (PC), permitting Meade Epoch 2000sk astronomical software to run the telescope, or to download new object locations and software from the Internet through a PC. The second cable directly connects two Autostars together, permitting full download capabilities from one #497 Autostar to the other.

Eyepieces: Meade Super Plössl (SP), Super Wide Angle (SWA), and Ultra Wide Angle (UWA) Eyepieces in the standard American-size (1.25") barrel diameter (Fig. 23) permit a wide range of magnifying powers with the ETX-90EC. Powers obtain-ed with each available eyepiece are shown in the following table:
EyepieceMagnifying Power
with ETX-90EC
With #126
2X Barlow Lens
SP 6.4mm195X390X **
SP 9.7mm129X258X
SP 12.4mm101X202X
SP 15mm83X166X
SP 20mm63X126X
SP 26mm *48X96X
SP 32mm39X78X
SP 40mm31X62X
SWA 13.8mm91X182X
SWA 18mm69X138X
SWA 24.5mm51X102X
UWA 4.7mm266XN/A
UWA 6.7mm187X374X **
* Included as standard equipment with the ETX-90EC telescope.
** Use these eyepieces only under extremely steady atmospheric conditions.

Fig. 23: Optional eyepieces yield higher and lower magnifying powers with the telescope.
Meade Super Plössl and Super Wide Angle Eyepieces are ideal for general-purpose astronomical or terrestrial observing. The typical ETX-90EC user may wish to add two or three of these eyepieces to his or her telescope. An introductory selection might include the SP 9.7mm and SP 15mm eyepieces, while the more advanced observer might select the SP 9.7mm, SP 12.4mm, and SWA 18mm. Meade Super Wide Angle Eyepieces yield extremely wide fields of view, perfect for the examination of star fields, diffuse nebulae, or for terrestrial applications. Under steady seeing conditions Meade UWA 4.7mm and 6.7mm eyepieces present the widest fields of view obtainable at high powers and are excellent eyepieces for viewing the Moon and planets.

#126 2x Barlow Lens: An amplifying lens, the #126 2x Barlow Lens (Fig. 24) doubles the powers of each eyepiece with which it is used. Insert the #126 into the telescope's eyepiece-holder first, followed by an eyepiece. Example: By itself the SP 26mm eyepiece yields a power of 48X with the ETX-90EC; when used in conjunction with the #126 2x Barlow Lens, this eyepiece yields 96X.

The Meade #126 is an achromatic, high-performance, short-focus Barlow Lens, perfectly suited to the low-profile design of the ETX-90EC. Lens surfaces are multi-coated for maximum image contrast and light transmission.

Fig. 24: Use the #126 2x Barlow Lens to double the magnification of the eyepiece employed.

Fig. 25: #825 Right-Angle Viewfinder.
#825 8 x 25mm Right-Angle Viewfinder: Similar in optical characteristics to the 8 x 21mm straight-through viewfinder supplied as standard-equipment with the ETX-90EC, the #825 right-angle viewfinder (Fig. 25) allows for a comfortable 90° viewing position. The #825 viewfinder replaces the standard-equipment 8 x 21mm viewfinder and fits into the same bracket on the telescope.

Fig. 26: Astronomical photography with the ETX. (1) #64 T-Adapter; (2) Standard Tripod Leg; (3) Fixed Tripod Legs; (4) #1422 Low-Latitude Balance Weight.

Fig. 27: (1) High-Latitude Tripod Leg; (2) Thumbscrew Lock.
#64 T-Adapter: The #64 T-Adapter (1, Fig. 26) is the basic means of photography through the ETX-90EC. The adapter threads to the rear cell of the telescope, followed by a T-Mount appropriate to your brand of 35mm camera. With the #64 T-Adapter and T-Mount in place, the camera body is rigidly coupled to the telescope's optical system, which in effect becomes the camera's lens.

#880 Table Tripod: Lightweight and extremely portable, the #880 Table Tripod (2 and 3, Fig. 26) attaches quickly to the telescope drive base and provides a sturdy platform for astronomical viewing. Two identical fixed tripod legs (3, Fig. 26) mount to holes on the side of the drive base. The adjustable standard tripod leg (2, Fig. 26), with its two latitude scales, is mounted to one of two holes on the bottom of the drive base and permits the telescope to be polar aligned for latitudes between 22° and 48.5°. At higher observing latitudes the shorter high-latitude tripod leg, also included and shown in Fig. 27, is substituted for the standard tripod leg.

#1422 Low-Latitude Balance Weight: If the ETX-90EC is to be used with the #880 Table Tripod and polar-aligned at latitudes below 30°, the telescope can become unbalanced, particularly if heavier accessories (e.g., a camera body) are attached to the eyepiece-end of the telescope. The #1422 Low-Latitude Balance Weight (4, Fig. 26) slides on to the standard tripod leg and enables rock-solid stability of the telescope even at lower latitudes.

Fig. 28: The #883 Deluxe Field Tripod with ETX-90EC Telescope, set up in the Alt/Az configuration (tripod head locked at 90°), for terrestrial applications. (Inset) Tripod head tilted for polar alignment.
#883 Deluxe Field Tripod: Manufactured of strong, lightweight extruded aluminum, the #883 Deluxe Field Tripod (Fig. 28) allows standing or seated observations through the ETX-90EC. Tripod height is continuously adjustable from 34" to 54". Micrometric controls in both azimuth and elevation-angle permit precise polar alignment of the telescope's fork mount for astronomical applications. Designed exclusively for ETX-series astronomical telescopes, the #883 Deluxe Field Tripod includes all the rigidity and stability required for high-power observing through the telescope. For terrestrial observing, where altazimuth orientation of the telescope is desirable, the tripod head tilts and locks at 90° (inset, Fig 28).

#882 Standard Field Tripod: (not shown) If the ETX-90EC is used primarily for terrestrial observing and less-extensively for astronomical viewing, the polar alignment capability of the #883 Deluxe Field Tripod may not be required. In this case the #882 Standard Field Tripod provides a rigid observing platform for the telescope in the altazimuth (Alt/Az) configuration, only. Alternately, if the telescope is equipped with the optional #497 ETX Autostar Computer Controller, astronomical sidereal-rate tracking can be effected in the Alt/Az configuration permitted with the #882 Standard Field Tripod, without any requirement for polar alignment. The #882 Standard Field Tripod is variable in height between 34" and 54" for seated or standing observing through the telescope.

Fig. 29: The #932 45° Erecting Prism threaded to the rear cell of the ETX-90EC. (1) #932 45° Erecting Prism; (2) Eyepiece; (3) Knurled Lock-ring; (4) Flip-Mirror Control.
#932 45° Erecting Prism: If the ETX-90EC is to be used for extensive terrestrial applications, the #932 45° Erecting Prism (1, Fig. 29) is a useful accessory. Images through the 90° eyepiece-holder (4, Fig. 1) appear right-side-up, but reversed left-for-right. The #932 Prism threads on to the telescope's photo port (17, Fig. 1) and presents a correctly oriented image as well as a convenient 45° observing angle. An eyepiece of any focal length (magnifying power) may be inserted into the #932 Prism. Note that the flip-mirror control (4, Fig. 29) must be in the "down" position for use with the #932 Prism.

Important Note: In the most discriminating applications, such as in observing delicate bird feather-structure at long distance, the ETX-90EC's internal, optically-flat mirror yields a higher-resolution image than is possible with any prism, including the #932. In these special cases ETX-90EC users are advised to observe with the eyepiece in the standard 90° eyepiece-holder (as shown in Fig. 1), with the flip-mirror control in the "up" position. This admonition applies only to situations requiring extraordinarily high optical resolution and where the observer's eye is well-trained to observe very fine detail. In typical terrestrial applications, no image differences between the two eyepiece locations can generally be noted.

#765 Soft Carrying Bag: Perfectly suited to field use of, or traveling with, the telescope, the soft-padded, Cordura-type #765 Soft Carrying Bag (Fig. 30) for the ETX-90EC includes a shoulder strap and permits ready transport of the complete telescope, including the table tripod, eyepieces, and other accessories. With the #765 Soft Carrying Bag the telescope can go anywhere with you at a moment's notice.

Fig. 30: The #765 Soft Carrying Bag.

Fig. 31: #774 Hard Carrying Case.
#774 Hard Carrying Case: For situations that require ruggedness and portability, the #774 Hard Carrying Case (Fig. 31) provides a secure environment for the ETX-90EC. The fitted foam interior protects the telescope while providing ample room for additional eyepieces, a table tripod, the Electronic Controller, ETX Autostar, and much more.

#607 DC Power Cord: To power the ETX-90EC from an automobile cigarette lighter plug, the #607 DC Power Cord (Fig. 32) is required. Supplied with 25 ft. cord.

Fig. 32: #607 DC Power Cord.

#541 AC Adapter: (not shown) The #541 AC Adapter permits powering of the ETX-90EC via a standard household (115vAC) electrical outlet. Supplied with 25 foot cord.

#1244 Electric Focuser: The #1244 Focuser (Fig. 33) replaces the manual focuser knob of the ETX-90EC and permits smooth, precise electric focusing of the image through a remote handbox supplied with the focuser. Alternately, on the ETX-90EC, the #1244 Focuser may be plugged into the telescope's computer control panel and operated through either the Electronic Controller or the optional #497 ETX Autostar Computer Controller.

Fig. 33: #1244 Electric Focuser.

Fig. 34: (1) #905 Variable Polarizing Filter; (2) Eyepiece.
#905 Variable Polarizing Filter: For glare reduction in observing the Moon the #905 Variable Polarizer (Fig. 34) includes two Polarizer filters mounted in a specially-machined cell. The #905 permits variable settings of light transmission between 5% and 25%, to account for varying lunar surface brightness according to the phase of the Moon. Accepts 1.25" barrel-diameter eye-pieces of any focal length.

Fig. 35: Epoch 2000sk software
Epoch 2000sk Sky Software: Meade Epoch 2000sk astro-nomical software (Fig. 35) has created a revolution in the way amateur astronomers prepare for observing sessions at the tele-scope. For Epoch 2000sk presents on the display of a personal computer an incredibly detailed simulation of the entire sky, including up to 281,000 celestial objects. Epoch 2000sk allows the presentation of the most complex star fields just as they actually appear through the telescope. And yet, notwithstanding its precision and detail, Epoch 2000sk is easy and intuitive to use, even by the novice. Epoch 2000sk operates the ETX-90EC through a laptop computer in the field using the #497 Autostar Computer Controller and #505 Connector Cable Set. Epoch 2000sk astronomical software is available in the following formats:

  • Epoch 2000sk-JR: 10,000 objects supplied on 3.5" discs for Windows 3.1 or higher, or Windows 95.
  • Epoch 2000sk Sky Software: 281,000 objects supplied on 3.5" discs for Windows 3.1 or higher, or Windows 95.
  • Epoch 2000sk-CD Sky Software: Over 19 million objects supplied on CD-ROM for Windows 3.1 or higher, or Windows 95.

Chapter 6: Maintenance and Servicing

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