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The iOptron MiniTower - Part 2


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Since March, I have spent countless hours working with and testing iOptron products. With the MiniTower, I tried several scopes in various locations at various hours of the day and night. In the course of doing so, I became acquainted with Dr. John Hou at iOptron and Steven Forbes at Trapezium Telescopes, the latter of whom is a dealer specializing in iOptron products. I am going to spare readers many of the details of this exercise. Hence, what follows is a summary of my experience with this product and my conclusion as to its suitability.

First, I am convinced that iOptron, a young company, wants to develop quality products and, since my March review, it has engaged in a program of quality control improvement. For example, Dr. Hou contacted me shortly after my review was published to request further testing of different iterations of the product. iOptron had my review translated into Chinese and sent to their manufacturing facilities in China so that those who actually assemble the product would have first-hand knowledge of the issues that arose. It has also developed and made available new and better versions of its hand controller software. iOptron also apparently published a response to my initial review of the MiniTower, but I have not been able to locate it.

The work leading to my previous review was conducted in Colorado. Shortly after concluding that work and submitting my review to Cloudy Nights,1 I returned to Michigan, carrying the MiniTower head and controller only. I did not expect to return to Colorado until August and anticipated that replacement gear would be provided for further testing. That in fact happened.2

Initially, it was suggested by iOptron that the reason for the vibrations to which I referred was not faulty gear, but instead the fact that it was set up on a wooden deck. While this is a plausible hypothesis, that deck is quite stable, and I did not believe it to be the cause. But I wanted to double-check. So I set the unit up (using the tripod provided with the replacement unit) on the tarmac outside of our Michigan cottage. Sure enough, a change of scenery had not resolved the problem. The MiniTower behaved exactly as it had in Colorado, this time loaded with a 90mm refractor.3 So, at iOptron’s request, I packaged the unit up and sent it to Massachusetts for testing. Sometime thereafter, I set out to test the replacement unit, which had its own new hand controller.

In addition to trying the new unit with my 90mm refractor, I decided to see how it would handle a little weight and, hence, attached my 5.1 inch (130mm) refractor. I used the counterweight with the latter scope; I used only the counterweight bar with the 90 mm refractor. The unit handled both refractors equally well. I was careful to balance both scopes prior to use, extending the dew shields and setting a focuser length that represented what would be required to place a “typical” eyepiece in focus. Despite my concern about the additional weight of the 130mm refractor, there was absolutely no problem. The unit did not even seem to be challenged. A photo of the MiniTower with the 130mm refractor follows.


After testing the replacement unit under weight, I decided to see how it would operate under actual observing conditions, using the 90mm refractor. First, I tried a daylight test employing a hydrogen alpha filter to observe the currently “spotless” sun. The unit behaved well, and I enjoyed seeing several interesting solar flares. To test its tracking ability, I left the MiniTower focused on the sun while I ran errands for about an hour. When I returned, the sun was still visible in the 13mm eyepiece, albeit only partially. So, its tracking seemed acceptable, if not exemplary. But I did not have the controller set to solar tracking speed, and I suspect that is why it did not track quite as well as I had hoped.

That night, I set the replacement unit up on a wooden deck at our cottage. Saturn was high in the sky, as were a number of Spring constellations. Once aligned, the “go to” function was remarkably accurate. Using the 90mm refractor, the unit placed selected objects uniformly in the center of a 13mm eyepiece. Saturn was particularly lovely that night, and I spent some time just looking at it. I then decided to once again test the tracking and left the mount focused on Saturn in a 4mm eyepiece. Believe it or not, over two hours later, when I returned to the scope, Saturn was still in the center of that small ocular. As I stared at the ringed planet, I conjured up in my mind the favorable follow-up review I would write. Then, something odd happened. Saturn started jumping up and down. The mount had developed the hiccups! I turned it to Izar and then Arcturus. Was I crazy? No. The mount had indeed, after more than two hours’ use, developed an odd vertical leap. I couldn’t believe it. I tried the mount again the next night on the tarmac, and it did the same thing. Suspecting that the problem might be in the software rather than the mount itself, I tried the controller on an iOptron Cube Pro (see my forthcoming review of that product), and it did the same thing. After about 45 minutes, it developed hiccups. Strange as it may seem, I was not, in fact, crazy. An independent and very reliable third-party source later verified the propensity of some of these units to develop a blip after extended use.

I promptly advised iOptron of the issue. iOptron provided a replacement controller—a Beta test unit—that had new software installed. The skies in Michigan were cloudy for a couple of weeks thereafter, but when we finally once again had a clear night, I once again set up the MiniTower on the wooden deck in front of our cottage and mounted the 90mm refractor to see if, at last, the problems were resolved. Instead of using the one-star align function (the alignment stars were not in view at that location), I elected to “select and slew” to a target and then synchronize the target to establish alignment (this is a good shorthand way of jumping into an observing session with a MiniTower). To my utter angst, however, when I pushed the “synchronize” button, instead of telling me to use the arrow keys to center the item before pushing “enter,” it simply flipped me back to the main screen and began tracking in celestial mode wherever it was then located. I tried several times with the same result. Needless to say, I was not pleased.

Once again having contacted iOptron and Mr. Forbes, I was sent yet a fourth hand controller. It was now July, I had calmed down a bit, and I tried the rig anew. This time, however, everything seemed to work fine—good alignment, acceptable tracking and no hiccups. But the real test would come back in Colorado.

I returned to the mountains in August and, as luck would have it, was greeted by two weeks of clear nights under a dark sky, giving me plenty of opportunity to test the MiniTower under the conditions for which it was purchased. I attached the 105mm refractor and put the mount to work. I put it through its paces for ten nights, leaving the MiniTower on for hours at a time. Its performance was, at last, exemplary. The “go to” function, once aligned, was extremely accurate throughout the Western Hemisphere of the late summer sky. It never missed, always putting the desired object in the field of view of a 12mm eyepiece, usually toward the center, even when slewing great distances and even when moving from nearly horizontal to fully vertical. The tracking did not seem quite as good as the night Saturn stayed with me for more than two hours, but it was certainly acceptable, if not better. I have thoroughly enjoyed these past two weeks with the MiniTower and am quite pleased with its performance. Note that I have been using the unit on the same wooden deck where I had originally had all the troubles with the first and second MiniTowers. There is no problem there with this one.

Is the mount perfect? No, I still have a few complaints, but for the most part they are relatively minor:

  1. The altitude clutch is just loose enough that, even when tightened, if when changing eyepieces, the one to be removed “sticks” a bit, the scope will move in altitude, losing its alignment. You should use "light fingers" when touching your scope on this mount. It also slipped out of altitude alignment when bumped by a child trying to peer through the telescope. It did the same thing on my final night in Colorado when I drew the focuser on the 105mm refractor out to lock in the view with a long focal length ocular. One would expect to find some sort of Teflon pad or other membrane that would allow the user to draw the altitude axis up tight. But there appears to be no practical way to accomplish that. iOptron should develop a solution.

  1. The hand controller buttons are not always responsive to anything but a direct, firm hit, and the words on the hand controller screen are sometimes hard to read.

  1. iOptron has still not resolved the cord wrap problem, although this unit seemed better than the previous ones.

  1. The star and double star catalogues in the hand controller software are principally SAO-based. This is not terribly user friendly if, for example, you are looking for epsilon lyrae. Who knows offhand what that target's SAO number is? Reference to some sort of conversion chart, such as that found a Taki's home page (http://www.asahi-net.or.jp/~zs3t-tk/index.htm) is required.

  1. The tripod, though sturdy, presented me with a particular problem. I am not tall, but with the tripod fully extended and the scope pointed to an altitude of higher than 30º, I found the need to observe in a bent-over position that ultimately created back strain. This was exacerbated when I used the 130mm refractor, with which viewing was downright uncomfortable. The solution? I purchased a Televue “Air Chair” which relieved the pain. I believe you will want to use an observing chair with this mount if you use a refractor of anything but a small size.

Anyway, I am through testing the MiniTower and offer the following thoughts to prospective purchasers: I believe iOptron has taken a major step forward toward acceptable quality control. That being said, I recommend that care be taken when purchasing units manufactured prior to May 2009. And, while I have dealt with all of the major astronomical supply houses in the country periodically over the past ten years with very satisfactory results and recommend those houses to you for most products, purchasers may wish to consider buying the MiniTower from a specialty supplier that tests the units before shipping them. That will reduce the risk of trouble down the line. Also, and importantly, the software on the hand controller should be dated July 2009 or later. If you have the hand controller with earlier software, iOptron has provided a method of downloading updates. It is not terribly user-friendly, but it does work. And you may need to remove the cover on the mount and tighten up the connection that established GPS contact (see my prior review). These wires tend to become loose in shipping (even the replacement unit I write about here is a bit slow to pick up GPS), but the fix is quite simple.

Finally, let me express my thanks to Dr. Hou and Mr. Forbes, who patiently listened to my complaints and supplied me with replacement equipment. Like almost everyone I have met in the amateur astronomical community, these are nice folks.

1 My previous review of the iOptron MiniTower, which was not altogether favorable, seems to have disappeared from the mount review section of Cloudy Nights. Odd. Anyway, readers can find it by searching "MiniTower" on the Cloudy Nights homepage.

2 In interest of full disclosure, readers should note that through Trapezium Telescopes, iOptron provided me with a second MiniTower outfit to test. iOptron requested that I send my unit for testing by them. I agreed to accept the replacement unit in exchange, subject to verification that it worked properly.

3 Note that there is a typographical error in my original review. Therein, I refer to my 105 mm refractor as being “5.1 inches.” Obviously, that is wrong. The refractor in question, which I used in Colorado, is 4.1 inches. As noted later in this article, that difference is of some significance.



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