Weasner's ETX FAQ

FREQUENTLY ASKED QUESTIONS

Last updated: 4 October 2011

Q. Which telescope should I buy?
A. Beginning in amateur astronomy is like beginning any hobby. You should understand what you want to get out of being an amateur astronomer, what you want to do with the telescope, and what your expectations are, and then you should do some research on available telescope models and capabilities. When it comes time to do the research, this web site can help a great deal with its actual user experiences. Besides all the user reports and feedback, see "What to Expect from Your Small Telescope". One other thing that you need to consider is the cost of the telescope and accessories. Keep in mind that low-cost telescopes may have some tradeoffs in design and performance. "Department Store" telescopes are not normally a good beginner's telescope; they can disappoint and frustrate the new user to the point where interest is lost. Buy a telescope from a well known manufacturer and from an established telescope dealer who will stand behind the sale (see the Dealers section on the Astronomy Links page for some good dealers). No one can tell you exactly what telescope to buy. Only you can determine whether an ETX or DS model is right for you. Certainly the ETX line has been very popular since 1996; for many users it is the right scope. There are many other fine telescopes that are right for other users. Know your requirements and do your research, then buy accordingly.

Q. What is the difference between the RA, EC, AT, PE, and LS models?
A. The RA model was the original ETX (non-AutoStar, 1996). The EC model (1999) added electronic slewing controls on both axes and came with a standard 4-speed handcontroller; the AutoStar and a tripod were additional cost options. As noted on the Announcements - Meade page on 15 June 2003, there is no real difference in the EC model vs the AT models; the standard handcontroller was no longer included (the EC model) but the AutoStar #497 and the #884 tripod were included as standard with the AT model. It was just a designation change. The PE (Premier Edition) model started shipping around 2006 and included the Level North Technology (LNT) module but otherwise is essentially the same as the AT model. Unlike earlier ETX models, the PE model dropped an optical finderscope in favor of a 1X "red-dot" finder. The ETX-LS started shipping in 2009 and was a major upgrade from earlier ETX models. It included GPS as well as the Level North capability. Unlike earlier models, the LS models are available in ACF (Advanced Coma Free) or SC (Schmidt-Cassegrain) optics. It also includes a built-in CCD camera for true Auto Align (the camera "sees" the alignment stars) as well as for wide-field astrophotography. The mount is a single fork arm, unlike the previous dual fork arm ETX models. Lastly, the ETX-LS came with a new model AutoStar, known as the AutoStar III. Also, see the "Q. What is the difference between the ETX-LS, LS, and LT models?" Shortly after announcing the ETX-LS model, Meade decided to remove the LS model from the ETX family. So, it is no longer considered an ETX telescope.

Q. What is the difference between the ETX-LS, LS, and LT models?
A. Sent: Monday, December 14, 2009 16:02:58
From: Meade Instruments
ETX-LS 6/LS-6: are the same LightSwitch, Astronomer Inside (built-in Audio), AutoStar III, Eclips CCD Module, GPS, Magnetic North Sensor Telescope. Flip a switch and Lightswitch technology Uses GPS, Magnetic North sensor, and level sensors to tell it where it is. Slew to a guide star and use the built-in CCD camera to center and verify the guide star. SC and ACF optic available. Built-in audio, and optional video display capability. The ETX-LS 6 telescope and the LS-6 Telescopes are one in the same. There is no design difference between the two, save for the name plate, and perhaps minor assembly differences that have been reflect lessons learned from the first units that have come off the line. Software architecture is unchanged. The "ETX" moniker was dropped because the "LS" mount share nothing in common with the ETX series. The "LS" series has a die-cast Aluminum mount and 4.875" diameter worm gears in both axis. In fact, the "LS" mount has more in common with the LX90 Series. As a result, it was decided to drop "ETX" to eliminate comparison and confusion between the two.

LT-6: LT series are AutoStar #497 based products. It is basically a 6", single fork arm LX90. No GPS, no LNT technology (level and magnetic north sensor). You have to manually enter time, date, and location. Manually level, point the tube north and manually verify the guide star. ACF and SC optical systems are available.

The LS and the LT are both single fork arm telescopes with 6" apertures, so they look very similar on the surface. They operate quite differently.

Mike here: There is now a family of LS and LT models. But as noted in above, the LS (LT) models are no longer in the ETX family.

Q. Are the ETX-90/105/125 base components interchangeable?
A. From Dr. Clay Sherrod: "Unfortunately there are NO common components unless some adaptations are made in brackets, spacing, and even some gears. All three are markedly different."

Q. How do I tell if my ETX has UHTC?
A. The UHTC label should appear on the bottom side of the OTA (Optical Tube Assembly). You can see a photo of this on my ETX-105PE comments on the Helpful Information: Buyer/New User Tips page.

Q. How do I upgrade a non-AutoStar ETX to an AutoStar capable ETX?
A. Short answer: you can't. Meade does not offer an upgrade for the original model ETX (also known as the ETX-90RA or ETX Astro M). But you can mount the OTA on a different mount (see the Telescope Tech Tips page) or (if still available) get a JMI computer system (see the "NGC-microMAX/NGC-MAX" on the Accessory Reviews - Miscellaneous page). Or you could sell it and by a new AT model.

Q. My Declination (altitude) setting circle is off, what do I do?
A. This is a common problem, especially on new scopes. The Declination scale can move during shipment or from telescope use over time. Unlock the DEC axis. Using a spirit or some other type of level, level both the telescope base and the optical tube, then tighten the DEC lock. Keeping things level, loosen the knob on the DEC scale fork arm a little bit and rotate the scale by hand until it reads zero (0) degrees under the pointer. Hold the scale in position and retighten the knob.

Q. The Right Ascension (azimuth) setting circle tape moves, what do I do?
A. The tape on the ETX is supposed to move to allow it to be adjusted for use. For more on using setting circles see "Using Setting Circles".

Q. One of the drive motors runs continuously but I don't see any movement of the telescope tube. Is something wrong?
A. Probably not. This is likely the Right Ascension drive motor running. When used for astronomical purposes, a telescope has to move in Right Ascension to compensate for the Earth's rotation. Otherwise objects would quickly move out of the eyepiece field-of-view. Like watching the hour hand on an analog clock, the movement is hard to detect as it takes nearly 24 hours to go completely around.

Q. I can not move the Right Ascension (azimuth) lever enough to fully engage the lock. What should I do?
A. Position the lever to the locked position (don't overdue it), loosen the setscrew in the side of the lock handle, lift the handle and reposition it more to the unlock direction, and then retighten the setscrew. Now you should have more distance to move the lock lever to lock the axis.

Q. I can not remove the aperture or rear port cover or loosen the Declination/Altitude scale knob. How do I loosen it?
A. I have successfully used rubber jar-lid removers to grip the cover to unscrew them. It is also been reported that putting an ice bag on the cover for about 30 seconds will also work.
And from Dr. Clay Sherrod for the aperture cover: "Very gently grasp the dust cover edge in your left hand with only three fingers; do not put any pressure on it at all; take your right hand with a rubber glove on it and very tightly hold the OTA to keep it from slipping; without pushing or twisting, merely turn with those three fingers...it will pop loose quickly if you keep trying."
Forrest Lundberg (flundberg77@comcast.net) provided this tip: "Carefully drill two 5/32 holes about 2 1/2 inches apart thru the cover. Use a stop on the drill so as not to hit the lens. the chips that fall through should not be a problem if you carefully remove them after getting the cover off. Now you can make a spanner wrench to fit the two holes from a piece of 1 x1/4 inch aluminum bar stock, drilling two 1/8 inch holes 2 1/2 inches apart and driving in two 1/8 inch roll pins. The holes could be filled with epoxy afterward."

Q. I have a spot on my ETX optics. How can I clean the optics safely?
A. See "Cleaning Optics" on the Buyer/New User Tips page.

Q. How do I calculate eyepiece magnification? What is the max?
A. Magnification is the telescope's focal length divided by the eyepiece's focal length. So, with the ETX-90 and the standard 26mm eyepiece you have 1250mm/26mm = 48X. The theoretical maximum "usable" magnification is typically twice the telescope aperture in millimeters (ETX-90 = 180x) or 50-60X per inch of aperture (ETX-125 5" = 250-300X). However, most times you will not be able to reach this limit except under excellent conditions and on bright objects (like the Moon and brighter planets). For more on magnification see "Telescope Performance III - Magnification".

Q. I am making an AC Adapter for the ETX. What is the Polarity of the center pin?
A. The center pin is positive.

Q. Where do I find manuals online?
A. Many Meade manuals, including DSX, several DS models, LX90, LXD55, and ETX, AutoStars, and AutoStar Suite, are available on Meade's web site. The Meade ETX-90/105/125 manual is here (PDF; Adobe Acrobat Reader required). A Meade DS manual here (PDF). The Meade #883 Deluxe Field Tripod manual is here (PDF). The LX90 manual (and excellent source of AutoStar 2.1ek and newer information). Bob White (gunta@socal.rr.com) has prepared this AutoStar manual (MS Word; 288K zipped). For information on writing Tours for the AutoStar, go here (PDF). The Astronomics web site has many older manuals available. DSI II instructional info is available at http://www.optcorp.com/product.aspx?pid=319-320-445-7840&tb=3.

Q. What is the size of the eyepiece holder screw?
A. By my measurements the eyepiece clamp screw used on ETX telescopes is a metric screw 3MM dia. by 0.5MM thread pitch. [from Forrest Lundberg]

A good source for replacements is Scopestuff (http://www.scopestuff.com/ss_scr1.htm).

Q. What is the HOME position?
A. The HOME position depends on the model and alignment mode you select. If you don't have a PE model (with the LNT), then there is only one Home position for the ETX-90/105/125: CCW to the hard stop and then back CW about 120 degrees to point the OTA to True North (the control panel will be on the west side). For the ETX-60/70/80, which don't have hard stops on the Azimuth axis, you just point the OTA to True North. For the PE model, if not using Auto Align, the Home position is the same as for the non-PE ETX-90/105/125. If using Auto Align on the PE models, then the Home position is CCW to the hard stop and leave it there (control panel still on the west side). For Alt/Az mounting, the OTA is always level. For Polar mounting, the OTA will be pointed at the North (or South) Celestial Pole. For more on the HOME position, see the "Alignment Tips" articles on the "AutoStar Information" page as well as the "Premier Edition / LNT Specific Tips" section on the Helpful Information: Telescope Tech Tips page.

Q. Should I use True North or Magnetic North for the HOME position?
A. The sky "rotates" around True North, not Magnetic North. So yes, you need to use True North. However, depending upon your location, you may be able to get away with using a compass. The difference in the two "norths" is called Magnetic Variation and varies from 0 degrees to nearly 20 degrees, depending upon your location on the Earth. If you are in a location where the difference is 15 degrees, your alignment stars will be a similar amount off. Once you get properly aligned the error is fixed. But it is obviously better to start with the proper North. In the Northern Hemisphere, the star Polaris (the "North Star") is within a degree of True North. See a star chart to find it. If you can't see it due to some obstruction, you can use a compass and just compensate for your Magnetic Variation (see one of the links on the Astronomy Links page). Don't forget to compensate for any nearby metal or magnetic sources!

Q. How do I enter Right Ascension and Declination and have the AutoStar GOTO it?
A. Simply hold down the "Mode" key for about three (3) seconds; if you have electric focus through the scope (not with the standard handbox) the first command you will see on the AutoStar readout is "Focus;" if you do NOT have the Meade electric focuser, then the first screen will show a Right Ascension and Declination that should be overhead at the particular time you are observing. Once you get to the RA and DEC screen then you press GO TO to change the readings of the RA. Press "Enter" and you will see that a cursor appears flashing on the first entry for R.A.; merely use the arrow keys to move and the number keys to key in the exact RA you want; once you are done with RA....YOU MUST PRESS ENTER again! That puts the cursor lighted up on the Declination reading which you again key in! If you need to change the sign just press the slew left arrow key to select the sign portion and then the down arrow (not slew down) to change to minus or up arrow to change to plus. Press "Enter" once more and it should go to those coordinates (if it does not, and merely displays them....press "GO TO" and the scope will move). If you have the Meade electric focuser, when you hold down "mode" you get the "focus" command; merely go down and tap you lower right "Scroll" key until you see a read-out of R.A. and DEC.; once there, press "Enter" and follow the previous instructions. That's all there is to it! [from Clay Sherrod]

Q. How do I upgrade the AutoStar with my Mac?
A. See the "Update AutoStar using a Mac" article. Also, see the AutoStarX link on the Helpful Information: AutoStar Info page. If you have an Intel-based Mac see the Helpful Information: Astronomy & Intel Macs page.

Q. What cable do I need to use an AutoStar?
A. See the "Cable Information" articles on the "AutoStar Information" page.

Q. How do I a make a #506 cable for the AutoStar #494?
A. The ETX-60AT and ETX-70AT with the #494 AutoStar requires the #506 cable. This cable includes some special electronics that are needed (unlike the #495 and #497 AutoStars). The specifications of these special electronics are not publicly available so you can't make a cable that will work with the #494. You have to purchase one from Meade.

Q. What model AutoStar works with what telescope?
A. See the "AutoStar Models" page.

Q. Does the AutoStar use positive or negative values for West Longitude?
A. In really old AutoStar versions, West Longitude was positive. It was changed in 1.1m to West being input as negative. That was true until version 2.1Ek and newer; they actually use the word EAST or WEST.

Q. My AutoStar is displaying a foreign language. How do I change it?
A. Turn on the telescope, press "ENTER" for the date, "ENTER" for the time, and then "ENTER" for Daylight Savings. Next press MODE once and then press the up arrow key (lower left of the keypad) once. Press ENTER twice to reset. You should now be at the language prompt. This assumes that your AutoStar ROM contains multiple languages.

Q. My AutoStar scrolls text too fast to read. How do I change it?
A. Use the arrow keys at the bottom of the AutoStar keypad to change scrolling speed. Press one and the speed increases; press the other and it slows down.

Q. My AutoStar says it is slewing when I try to GOTO an object but the telescope is not moving. What is wrong with it?
A. Try pressing [enter] before pressing [goto]. This is a very common "error"
("error", in that the User has to change their behaviour)
("error", in that Meade does not make this keystroke clear in the manual)
And further:
Whenever the AutoStar says "Slewing.." but doesn't move, the answer is always(*) "press ENTER before pressing GOTO"
Now why were the Tours behaving differently, you ask?
Because there are -two- ways to put an object in a tour. One is to just name it, as in "PLANET VENUS" and the other is to put the words "AUTO SELECT" in there, as in "AUTO SELECT PLANET VENUS"
The "AUTO SELECT" in effect presses the "Enter" for you. That's what the -auto- commands: "automatically select it", rather than merely present it as a possibility. Tonight's Best uses Auto Select.
* footnote: "always" = 99.5%
[from Dick Seymour]

Q. My telescope has gone berserk. It slews until it hits the hard stop in either azimuth or altitude. It behaves erratically. What do I do?
A. Generally this occurs when changing the power source, either by swapping in fresh batteries, switching to AC or a 12VDC source, or when the batteries run low and need replacing. Normally, doing a CALIBRATE MOTORS from the AutoStar will fix it. This is an automatic operation once you select it. Sometimes you may also need to do a TRAIN DRIVES. And on rare occasions you may need to RESET, CALIBRATE MOTORS, TRAIN DRIVES.

Q. I just updated my AutoStar with a newer from Meade's web site. Now my AutoStar GOTOs are acting funny; the GOTO completes, I center the object, but then the AutoStar slews it back to where it thought it was. What do I do?
A. Whenever you update the AutoStar, redoing the TRAIN DRIVES really helps to avoid this "rubberbanding". In fact I always CALIBRATE MOTORS and TRAIN DRIVES following an update.

Q. The power went off while I was updating my AutoStar and now it doesn't work. Did I kill it?
A. You need to do a SAFE LOAD. Power off the telescope. For the AutoStar #497 through version 4.3, hold down the ENTER and SCROLLDOWN keys (opposite corners of the AutoStar) and then power on the telescope. You will see something like FLASH LOAD READY. Launch the AutoStar Update application; it should detect this mode and let you reload the AutoStar. NOTE: this puts the AutoStar back in a "factory condition". You will have to re-enter your location, telescope type, mounting mode, CALIBRATE MOTORS, and TRAIN DRIVES. If you had any user objects in the AutoStar you will have to re-enter them as well. For versions starting with "59E" (so: 59E7, 59Ed, 59Ef) the sequence is simultaneous MODE and ?. For 5BE2 use ENTER and SCROLLDOWN. NOTE: There is no SAFE LOAD for the AutoStar #494. For more information on the SAFE LOAD procedure, see the article "Bad Download Recovery" on Helpful Information: AutoStar Info page.

Q. How can I tell what version of the AutoStar software (ROM) I have?
A. In the AutoStar menu, go to Setup > Statistics > Version.

Q. What is and when should I CALIBRATE MOTOR, CALIBRATE SENSORS, and TRAIN DRIVES?
A. CALIBRATE MOTOR should be done whenever the power source changes. So, swapping from internal batteries to an external source or vice versa. Also, when on batteries and the power level drops from usage, doing a CALIBRATE MOTOR will "retune" to the lower power level.

CALIBRATE SENSORS (models with the LNT module) normally only needs to be done when you suspect a pointing error could be due to leveling or magnetic errors. It is also useful on first use to refine the "Magnetic Variation" for your location.

TRAIN DRIVES should be done on first use and thereafter every few months. It should also be done after updating the AutoStar ROM. It should be done if you are seeing "rubberbanding" (which is when the AutoStar slews an object away from the center of the eyepiece FOV after you have manually centered it).

Doing any or all of these on every session does not normally hurt (unless you make an error) but it is not necessary to get full enjoyment from your telescope.