USER OBSERVATIONS Last updated: 11 November 2005

Subject:	Meade DSX-90AT User Review/Report
Sent:	Wednesday, November 9, 2005 07:28:40
From:	Glen Ilacqua (g_ilacqua@mac.com)
I did a quick review of this scope and it was published on Cloudy
Nights. If you think your readers would benefit from it, feel free to
use it, or any part of it. I'm really happy to contribute to this site.
It's been incredibly helpful to me.

Thanks,

Glen Ilacqua
126 Tolman St.
West Newton, MA  02465

It's been several years since I thought much about astronomy. Actually it was when Hale-Bopp came through that I last looked through a telescope. But I've always maintained an interest in looking skyward, so last month I decided to get a good, compact beginner scope that would be an all-around performer. I had assumed that quality optics on a GOTO mount would be out of my price range, but when I wandered over to the web-based Meade Factory Outlet store, I was surprised to see that they had the DSX-90AT on sale for $275 delivered. While familiar with the ubiquitous ETX line, I had never heard of the "DSX" designation before and the product is not described anywhere on the Meade site, so I was curious to see what they were selling.

So what is a DSX-90AT? This model is the same unit being sold at Brookstone for $495; although there are a few differences that I'll get into in a moment. Meade has taken the popular little 90mm f/13.8 Maksutov-Cassegrain OTA from the ETX line and mated it to the DS GOTO mount and tripod that is sold with all of the DS-2000 models. However, they've upgraded it with the Autostar 497 controller, rather than the 494 that comes with the rest of the DS-2000 Series. While the carton says that the scope comes with astronomical software, the special sale does not include it. The photo on the box also shows that the accessory tray should mount to the tripod spreaders. But the tray supplied is a simpler one that clips onto one of the tripod legs. The initial impression of the tray is flimsy yet functional. But the mounting clip broke during set-up the third time I used it. Otherwise the product is essentially an ETX OTA on a DS single arm mount. The package comes with the Autostar 497 hand controller, a Series 4000 Super Plossl 26mm eyepiece, the standard DS single arm mount, aluminum field tripod, and a straight-through refractor style 8x21 finder scope standard on most ETX90 models. At $275 delivered to any CONUS address, I could not resist in fact, a family member bought one too.

Meade says to allow 2 weeks for delivery, but the telescopes arrived exactly a week from the time I ordered them. One was delivered perfectly, the other was missing the holder for the finder scope. A call to Meade (and 27 minute on-hold time) got the order placed for the holder. A week later, the holder came, but did not include the mounting screws. Another call and another week wait, and everything was finally in hand. The process was a little annoying, but Mead's customer service was very efficient and pleasant if not a bit harried.

The DSX was packed nicely, and directions were detailed and well illustrated. However, several assembly steps such as attaching the mounting plate to the mounting arm were done at the factory, although the directions told you to do it as if it were not already complete. The entire assembly took about 15 minutes. It took another 15 minutes to align the finder scope. The DS Mount requires 8 AA batteries, not included. I had been reading on one of the ETX support sites that these DS mounts have a fair amount of backlash and slop in the drives (more about this later). The way to ensure some degree of accuracy in searching and tracking given the apparent loose tolerances in the drives is to "train" them. The owner's manual suggests that you perform the procedure every 3 months, or whenever you have an accuracy problem. The training procedure involves centering and slewing to and from a terrestrial target, and allows the controller to compare the calculated and actual movement of the drives and adjust the motion accordingly. The training took about 10 minutes.

My concern about choosing a 90mm Mak as a first scope was the limitations of the small aperture. And with a relatively long focal length of 1250mm, you end up looking at a small piece of the sky. But the combination of the price and the 497 Autostar seduced me. I've used this set-up a few times now in both suburban and rural settings. In addition to the Meade 26mm Super Plossl, I've used a Parks Gold Series 2x Barlow, 45mm and 35mm Paul Rini Eyepieces, a Celestron Omni 6mm Plossl, and an Orion Moon filter.

The first clear night happened to coincide with the full moon. In my excitement, I didn't even bother to align the scope. I simply plopped it down, slewed to the Moon and was immediately blown away. With the 26mm eyepiece (48x) the Moon just about fills the entire FOV. The image was crisp across the entire field. Even without a terminator to add depth and detail, it was easy to identify all of the major features on the Lunar surface. Adding the Moon filter and the Barlow got me to 96x and I had the sense that I was flying over Moon surface as I moved the scope across the portions of the large disk. Seeing conditions made the 6mm eyepiece (208x) less useful. So I spent several hours exploring at 96x for the remainder of the night.

On a night where the Moon was not so prominent, I decided to do a full alignment and see how the DS mount would help me find some deep sky objects. Mars was also at the peak of its opposition, so I was eager to see if I could make out some surface details.

The DS mount has a "Home" position from which you start your alignment process. The Home position is with the scope leveled and facing North. The Autostar offers three methods of alignment, and I chose the 2-star alignment that is reported to be the most accurate. Complete instructions on the Autostar alignment process can be found at:

With the 2-star alignment, you start from home position then choose two stars from the menu. Once selected, the mount slews to the object. The hand controller prompts you to center the star in the eyepiece. Once centered, you hit "enter" and it then slews to a second star that you select, and you repeat the process. You will then be told that alignment was successful. Each time I chose a star (I chose Capella and Betelgeuse because they were in the part of the sky viewable to me), the mount slewed to the object and it was pretty close to being in the eyepiece. With a little adjustment it was easy to synchronize. As soon as the alignment is complete, the scope immediately begins to track. While tracking, mount makes a humming sound. At first it seemed loud, but once used to it, I found it OK.

This is my first GOTO scope, so I have nothing to compare it to, but the movement of the drives seems pretty sloppy. This is particularly noticeable when you need to center an object after slewing while the mount is tracking. When you move the object left in the eyepiece and then hit "enter" to tell the computer to synchronize, the object will jump one half to two thirds of the way in the other direction as the tracking re-engages. Once you get a feel for it, you can plan for it in your adjustments, but it leaves a feeling that you don't really have precise control. Also, when manually slewing in the vertical plane at maximum speed, the motor sounds like it is turning for a few seconds, but the OTA does not move. Then suddenly, it jerks in the direction you are moving it, only to settle into a steady movement in that direction. Again, it can be worked around once you are accustomed to it, but it seems sloppy. Finally, you must be sure that the tripod is level, or you will have constant drifting problems while tracking. An inexpensive mini level or bubble level can be had a hardware store of a few dollars. Get one - use it every time you set up.

Once the alignment is completed, you can slew to any object in the 30,000 object library. I started with the Pleiades. At 28x with the 45mm eyepiece, the main cluster of the Seven Sisters could be seen in the FOV. The stars were pin-point sharp. Bumping magnification to 96x narrows the field, but you can just barely begin to see a little nebulousity around some of the stars. From there, I went off to the open cluster M34 in Perseus. It landed just outside the FOV, but a little fiddling and a re-synchronization and we were in business. At 48x, the dozen+ bright stars were clear and crisp, with about four times as many fainter stars also in the eyepiece. Mars was next. Overall, the view was disappointing. At 96x I got a nice pale salmon disk, but no features whatsoever. Due to the modest seeing conditions, the 6mm eyepiece was not useful. Several others who were viewing with me that night with 8" SCT's, reported similar results. By this time, Orion was rising, so I dialed up the Orion Nebula. At 28x with the big 45mm Rini, the Nebula was nicely framed and the main stars bright and sharp. At 96x, the trapezium was resolved as four clearly defined stars with a nice cottony, diffuse glow.

Replace the finder scope The straight-through 8x21 finder is optically inadequate. For any objects located higher than 45 degrees above the horizon, you must put your body in postures that should be reserved for religious martyrs. Spend the $49 and get the 90 degree 8x25 finder that is standard on the larger ETX scopes.

Get a flexible focus extender The tiny focus knob on the scope is tough to use. Its small radius is impossible to use with gloves. And on the DS mount small adjustments create vibrations and visual distortions. A flexible focus extender is a cable with a larger knob on the end. With its use, micro adjustments are possible with adult fingers regardless of the position of the scope, and they produce much less vibration.

Carefully consider your eyepieces With only 90mm to work with, light gathering is at a premium. When it comes to eyepieces, less is more. You may want to try designs with fewer elements like high quality Kellners and Modified Plossls that naturally serve up brighter images. When considering the narrow FOV offered by a long focal length such as this, opting for wide-angle eyepieces can be helpful. And a bigger eyepiece like a 45mm can make spotting objects easier.

Once familiarized with the DSX-90AT, the scope is a lot of fun to use. The OTA provides the same performance as the much more expensive ETX versions (without UHTC). With the addition of a few accessories, and working around some of the DS mount's quirks, the scope does everything you can expect of an instrument of its type. As a grab and go scope that will give breathtaking views of the Moon, and hold itself nicely with the planets and brighter deep sky objects, the DSX-90AT is a very satisfying performer. At the warehouse sale price of $275, I'm not sure there is anything else on the market that gives you the bang for the buck. At the full retail of $495, you'll have to make your own determination. But this is one satisfied customer.

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