2000-12-23 by Rick Towns
|Telescope:||Meade ETX 90/EC|
|Description:||90mm f/13.8 Maksutov Cassegrain, 8x26mm finder, 26mm Plossl eyepiece, $1295 CAD including AutoStar and Deluxe Field Tripod|
|Setup:||I traded in my C8 on the ETX so I could have a more portable package and GOTO control. I bought the ETX with the optional AutoStar controller and the Deluxe Field Tripod. This gave me a nice big mount with height adjustable aluminium legs and a tilting mount head, so I could polar align the ETX if required. I also got a 2x Barlow included in the deal, along with a nylon carry bag for the ETX.|
|Appearance:||The ETX is just about the best looking telescope on the market. Even years after it's introduction, that silkly blue tube and those purple & green coated Maksutov optics look just stellar from any angle. The metal screw on end cap lends an air of sophistication to the scope. Unfortunately, that's where the honeymoon ends. At the rear of the OTA, is a plastic housing that encloses the flip mirror system, a socket for 1.25 inch eyepiece and a camera port. The OTA is mounted in a flimsy plastic fork mount that has the electronics and batteries contained in the base. This whole assembly screws onto the tripod head via two thumb screws. Once assembled, the whole rig is reasonably sturdy, but there's a lot of slop in the fork mount and the base feels like it was made by Fisher Price. Both the base controller and the AutoStar have a decent feel to them, with a quality spiral cord and a good RJ-11 plug at the end. The AutoStar also features a nice red LED display that has brightness and contrast controls. The gears in the base and the fork mounts sound like they are made from cheap plastic, and when slewing, this thing sounds like a dentist drill on the verge of exploding!|
|Performance:||The ETX reminds me of a 1/3 scale LX-200. Mine was mounted on a sturdy field tripod,
with a head that could be adjusted from level (for Alt-Az mode) to the appropriate
angle for polar alignment. The ETX itself can be switched between the modes, and I
found myself using polar mode quite a bit, as it only required the RA motor to do
it's tracking, instead of both motors.
The ETX with AutoStar works very similarly to the much more expensive LX-200 mounts. You set up the scope, level the tube and aim it north. Then, initiate a two star alignment at which point the ETX will slew (noisily) towards the first star. The control pad will inform you of what star it wants, and you just need to center the star and press enter. Repeat for star number two, and the ETX will figure out the rest. You can now use GOTO for the rest of the night (as long as you don't bump the tripod!).
I was truly amazed at the accuracy of the GOTO system, given the ETX's modest price. My example had a few gremlins in it that prevented alignment sometimes, but when I did get it aligned, it worked flawlessly. Additionally, my wife April was able to connect the ETX to our laptop computer, then using a program called Starry Night, she could point and click on an object on the computer, and the ETX would go right to it! By far, that is the coolest thing I've witnessed as far as electronics and telescopes go.
It's also nice to see that the optics are up to the task as well as the gizmos. The 3.5 inch Maksutov scope was properly collimated and gave super sharp images of whatever we looked at. Stars were sharp to the edge of the field of view and showed superb colour contrast on doubles like Alberio, and it's long focal length facilitates the use of high power. I took the scope up to 170x plus routinely and was rewarded with sharp images. The views of the moon were excellent with decent contrast considering the obstructed layout of the optics. Planetary performance was very good - detail was evident both on Mars and Jupiter, the GRS was viewed and the Cassini Division on Saturn was descernable. Deep sky ability is decent with M13 showing some resolved stars at the very edge, and brighter galaxies like M81/82 showing some hint of detail. This is not a deep sky bucket by any means, but as a portable GOTO performer, the optics will certainly show you good images. However, the GOTO is a little limited by the fact that most of the 64,000 object database isn't really viewable through the modest 90mm aperture.
The tiny focus knob, and the fixed position of the eyepiece make for some awkward situations. Indeed, the best time I had with this ETX was removing the tube from the forks, and putting it on a camera tripod for a trip up north. April and I spent a wonderful evening on the 3rd floor south facing balcony of our suite, and bagged a pile of Messier objects in Sagittarius. When back on the mount, power is required to slew the scope (there are no manual movement knobs), and the batteries (8 AA's!) are good for about 40 hours of use. The basic controller doesn't have the GOTO capability, but it does have the N-S-E-W directions and slewing speeds for polar use.
There are many options you can buy for the ETX, and most importantly is a dew cap of some sort, as the meniscus lens is a condensation magnet! You can also get an electronic focuser that works right with the standard and AutoStar controllers - that would certainly make life easier!
|Conclusions:||Overall this scope is an excellent performer. The 90mm Maksutov optics are awesome -
as good as a Questar 3.5's (I had a chance to compare them head to head over a 2
month period). The over use of plastic is somewhat alarming, and I question the
longevity of the system's moving parts over the long term.
The bottom line? Recommended (fantastic GOTO and optics housed in a decent package).
My name is Rick Towns and I am an amateur astronomer and computer programmer from Canada. This is a collection of interesting posts I've gathered over the years.