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Ioptron Mini tower _ New Review is Unsettling

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#51 Astrobuddy


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Posted 05 April 2009 - 11:06 AM

Another thing I would like to share is about the "to park position." John mentioned “I pushed “to park position,” and waited for the motors to engage as the manual said they would. Nothing happened. So, I manually aligned the scope in a vertical position, using a level to ensure precision, pushed "to park position" again, and shut the power off.” Actually I would not expect the motor move if the first thing was “to park position” when power on. The initial (default) position when power on is park position no matter whether it actually is. If after slew and then to park position, I bet the motor would move.

Yes,the initial position is park position when turn on the unit. I always park the mount before power off. Whenever I start a new session, the mount will right be at work. Otherwise, the OTA might point to the ground when slewed to the sky.

#52 watcher



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Posted 05 April 2009 - 06:46 PM

I know iOptron has at least 1 moron working in their assembly department. My GOTONOVA RA motor is attatched with 3 screws. 2 out of 3 of the screw holes were stripped, and the gear placed on the unit like there was nothing wrong. I've done that type of assembly work before. There's no way whoever assembled my unit didn't know that he or she messed up.


#53 NotThePainter


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Posted 05 April 2009 - 10:22 PM

Re: ASGT vs Mini Tower

I own both of them. I've barely used my MT because it is so new to me, but I've had my ASGT for quite a long time. I did something today that my ASGT could never do. I set it up, rough guessing where South was (North for the ASGT obviously), slewed to the Sun. Then manually slewed to the Sun, then sync'd on the Sun.

Then we slewed to Capella and it was in the FOV about 2/3rds of a degree from center. The ASGT can't dream of doing that. Don't get me wrong, I love my ASGT, but the MT is a fine piece of equipment at least with regards to initial GoTos. I know that after 2 alignment stars and 2 calibration stars that the ASGT will be dead nuts on. But frankly, the MT impresses me out of the box. More to come late when I actually finally get to USE it!

Oh, the MT did one more thing next that the ASGT couldn't do. My 15 year old daughter and I packed everything up and carried it all to the basement ... in one trip! I had the C8, MT case and solar filter, she had the tripod in its box, the eyepiece case and the C8 accessory case.


#54 jrbarnett


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Posted 06 April 2009 - 10:15 AM

How does the iOptron MT stack up to the Vixen Skypod?

The latter comes with a 5-year warranty, but I've read that Starbook is a work-in-progress.



#55 sam32


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Posted 06 April 2009 - 02:33 PM


I also have a MT but haven't yet tried to use it for AP. With respect to field rotation, doesn't it matter where you are pointing in the sky ? I mean if your target is closer to the NCP, wouldn't you be able to shoot for somewhat longer than 56 seconds ?



#56 J_D_Metzger


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Posted 06 April 2009 - 03:50 PM

iOptron has posted a statement in response to the review on the iOptron Yahoo Group:


#57 Dr Benway

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Posted 06 April 2009 - 04:38 PM


You are probably right about being near NCP. I noticed that I can't shoot 56 seconds at Zenith. I have a slight circular star track pattern. I have found halfway between horizon and zenith works well. I might be able to push beyond 56 on a subject like M81 M82. Steve has finished the prototype stage on the wedge project and it will be manufactured by ADM in the near future. All I really need is 2 minutes unguided, so I think the wedge will work fine for me.


#58 hudson_yak


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Posted 06 April 2009 - 04:42 PM

I also have a MT but haven't yet tried to use it for AP. With respect to field rotation, doesn't it matter where you are pointing in the sky ? I mean if your target is closer to the NCP, wouldn't you be able to shoot for somewhat longer than 56 seconds ?

Don't want to sidetrack this thread too much, but I was interested in the answer to this and found this good web page. It's complicated but the short answer is the least rotation happens when pointing straight East or West and the lower altitude the better.


#59 Dan Duriscoe

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Posted 06 April 2009 - 05:22 PM

Purchased the Mini Tower in November for our program. My first evaluation was somewhat lukewarm, and favor the Nexstar series. Yesterday I was prompted to re-visit the Mini Tower, so I took it completely apart. What I found surprised me, thought folks on this thread might be interested:

The tapered roller bearing design for BOTH axes is so simple and elegant it is amazing no other manufacturer has come up with this before now (this is 1940s technology). This is a bomb-proof way to carry weight and have smooth motion in both axes for many years to come.

The worm and worm gear design for both axes is pretty good. Both worm gears are manually clutched which is great--however adjusting these "clamping screws" is not trivial, especially the altitude clamp. It desparately needs more leverage and a locking device for those who want to use the mount manually (without the motors or GOTO features), which is something this mount could really excel at.

The nylon gear and motor blocks (which also carry the bronze worms) seem very under-designed and prone to wear. The fact that there is a company advertizing "tune-ups" for this mount speak to the fact that it does and will require "tune-ups" in the future, primarily because of this motor and gearbox design, I believe.

The gearboxes are mated to the worm gears with an ingenious spring design which takes up any play between the worm and worm gear. The nylon block is allowed to pivot and "float", with the spring forcing the worm against the worm gear. Metal stops at each side of the block (which are adjustable, and will probably need to be adjusted after some wear occurs) prevent backlash from left to right motion of the whole block. The nylon bearings for the worm shaft itself, however, seem under-designed and will probably wear with time.

The software has some very nice features, but also is in a growning pain stage. If this company survives, and responds to comments from its users, this is bound to improve with time. Communication with the Mini Tower via the iOptron ASCOM driver I have found frustrating. The Astro-Physics driver seems to work better in some cases. I hope a more complete set of commands will eventually become available. Also, I find the claim of 1 arc minute pointing accuracy, even when painstakingly aligned, some what overly optimistic. 5 arc minutes is more reasonable, but still VERY good for a portable mass produced mount.

The noise and jerkiness of the drive is a real issue. If you are annoyed by squealing and purring noises that seem to be random while observing, this is not the mount for you. If you observe at very high magnifications often, a German Equatorial is probably a better choice anyway.

In summary, the smoothness and durability of the tapered roller bearing design, with adjustable bearing preload available to the user, and the ability to take it apart, clean it, and re-grease it when necessary, all this in a very small and realtively lightweight space, is this mount's most endearing feature. It resembles a high quality surveyor's theodolite in this regard. However, the drives, software, and computer interface have some room for improvement. Also, if the clutches could be locked in a "semi-slip" position and stay there, this mount would rival the smoothest Dobsonian design for an untracked "just push it around and look" mount, and would provide an ideal platform for two small RFTs or a pair of big binoculars.

#60 Wes James

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Posted 07 April 2009 - 07:30 AM

I read iOptron's reply on the Yahoo forum... and I myself wrote them a letter yesterday- and received a very similar reply. At least the company is responsive. I hope they take these criticism's to heart and correct problems as they are noted. Their responsiveness certainly is better than some of the major players, and that I find heartening. I'd rather deal with a company like that- where they are at least interested in their customers- and responsive- rather than a company who totally ignores problems like this- and their customers complaints.

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