Meade ETX-125



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Date: 7-24-2001
Price: approx $700.00
Design: Small Cassegrain telescope that is very portable
Description: 125mm Cassegrain telescope that has optional computer controls.


I've owned an ETX125 for about 15 months. Bought it new from Astronomics along with Autostar, Meade's 883 tripod, and a hard case. 

1. Optical performance 

Optically it seems very good: de-focused star images show no distortion either side of focus although the relative brightness of the rings does vary some. Being inexperienced, I can't tell whether it's over-corrected or under-corrected. Image shift is only there if you look for it and is not an issue for visual observing. Brightness, however, is an issue and possibly contrast as well. The images just seem to lack 'pizazz' and appear somewhat dull and lackluster. Since I've only looked through one other catadioptric scope in my life (an 8" Celestron); I may be griping about a common failing of this type of scope. The Celestron's images weren't any better than the ETX's in this regard. With the eyepieces I have, I can get up to about 380X on this scope (10mm Orion Ultrascopic & Celestron Ultima barlow). This level of magnification is only useful on double stars and is about as high as I care to go. Whether this is because of the local seeing conditions or the scope, I'm not sure. The scope needs at least an hour to reach thermal equilibrium before delivering good images.

2. Performance on Planets 

Not what I'd hoped for. Could see 2 or 3 bands on Jupiter but no detail in the bands. Boundaries between the bands were indistinct. Could see a single ring division on Saturn and thought I saw evidence of banding on the disk; but it was indistinct. Haven't seen any details yet on the Martian disk. Some of this may be due to poor seeing. I view from a rural Midwestern site with little light pollution; but the sky always seems sort of 'milky' blue during clear days. A high thin cirro-stratus cloud layer seems to be a permanent fixture here even in a 'clear' sky.

On the night of 16 June 01 I thought I saw Deimos with averted vision. Referring to S&T's recent article on the Martian moons, I convinced myself that what I saw was in the right location. However, when I tried again a week later at a time when separation should have been greater, there was nothing to be seen. 

3. Performance on Double Stars 

Easily split gamma-Leonis and Polaris. Castor was a little tougher, but it was cleanly split at 380X (The Airey rings looked like flames from a gas-stove burner; constantly in motion---due to upper level winds?). Epsilon-Lyra, the double-double, is right at the limit. You can see the A & B components are both double; but just barely. It appears that the scope is much better on bright doubles than dim.

4. Deep Space Performance 

On the brighter deep sky objects, it's better than I expected. The images appear to have as much or more detail than I saw in the 10" f5.6 Dobsonian I once owned. Maybe this is due to the longer focal length. It might also be due to the GoTo putting me on the target quicker resulting in a fresher observer. The trapezium looks as good to me in the ETX as it did in the Dob. M31 looks better.

Haven't pursued the smaller/dimmer targets enough to judge performance. M97 has, to date, been a no-show in this scope.

5. GoTo and Tracking 

Will put selected targets in the finder field and sometimes in the field of the 26mm eyepiece IF: 

1) I've carefully trained the motors 
2) I've been exacting in my alignment 
3) I've carefully leveled the tripod before doing the alignment 
4) The tripod's level status hasn't changed during the viewing session 
    -one leg hasn't sunk into the ground more than the others 
5) I haven't bumped the thing 

Tracking is noticeably better in polar mode; in alt-azimuth mode it needs to be touched up every 3 or 4 minutes to keep object centered in eyepiece. In both modes, it seems to go through a stabilization period following any corrective input. If you can wait this period out, it settles down and tracks well enough for visual use. Gear backlash can make tracking corrections somewhat frustrating. This scope is probably a poor choice for astro-photography.

Autostar has only locked up on me once. It also ran the scope into the hard stops once. Other than that, it's been trouble free.

6. Mounts 

The Meade #883 tripod is adequate only in alt-azimuth mode. In polar mode the whole thing is in danger of tipping over as the offset weight of the ETX125 is just too much for it. This tripod appears to have been designed for the ETX90 and would probably work fine in either mode with that scope. There is a spirit-level on the head casting and the legs adjust to permit tripod leveling. Because of the polar mode deficiencies; I swapped mine for the #887 tripod

The #887 includes a for-real wedge and appears to have been designed for the LX10 8"SCT. The ETX can be mounted for either alt-azimuth or polar mode operation. Whichever is chosen it's rock solid on this mount. However, there is no spirit-level and there is no way to adjust the legs to level the tripod; they are fixed length. So bring your own level and a pack of playing cards (or something else that can be used to shim the legs).

7. Finder 

My first exposure to a right-angle finder and I really like it. Star field motions in response to a control input are the same in the finder as in the scope eyepiece. This makes it much easier to use. The crosshairs seem quite thick and it is possible for a target to hide behind them. Moving the eye back and forth from eyepiece to finder is quick and convenient and doesn't require different contortions. Anyone using the ETX90's straight-thru finder should consider upgrading to this. It's the first optical finder (as opposed to red dot-electronic) that I've found to be useful. Eyepiece can be focused; however a good center-field focus will result in slightly out-of-focus images at the edge of field.

8. Manual 

The worst part of the package. This goes for both the ETX manual and the Autostar manual. Not well organized, important information missing. I'm still discovering Autostar capabilities that the manual does not even hint at. It would be easy for the inexperienced to get totally turned-off on the ETX simply on the basis of its weak documentation. I AM inexperienced but, thanks to a background in robotics, was able to read between the lines enough to avoid some pitfalls. Step-by-step examples would improve both manuals, especially Autostar's. 

All-in-all; not a bad package for the price. I bought this system to find out what GoTo scopes were all about. I've found the feature useful enough to now seriously consider buying an LX200. GoTo is great for someone who observes sporadically and may not be too sharp on exactly where everything is. It's also great for sharing some of astronomy's finest sights with non-astronomer friends. And when the seeing isn't too hot, just watching the little beast gyrate around can be fun.

Submitted by Bob Young - YoungRF@TCE.COM - USA

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