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Getting to know G11 - II

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#1 nganga


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Posted 22 April 2013 - 10:32 PM

Getting to Know G11 - II

General Appearance:
This is an execptionally well made instrument. All the parts fit with no slop or slack. Nothing feels trivial or like a trinket. But there are many parts. Each leg has 2 segments, with 2 leg clamps and one positioning screw per leg; 3 knobs to lock the equatorial head to the mini-pier; 2 screws to hold each servomotor to the gearboxes; 2 bolts in the latitude locking mechanism; 1 large spring-loaded knob to slide the V-type dovetail and lock it in place. It is easy to imagine that if everything is not locked tight that some minute shift could occur under a large and heavy load.

It is heavy when fully assembled. For mobile use, one would not necessarily consider this a portable mount, but it can be carried short distances. I am able to carry it in and out of the garage, and I am an ectomorphic geezer.

I would not call this a pretty mount. Yet it is elegant, in the way that some military hardware can be elegant.

The mount has run well so far off my 12 volt 22Ah battery, through a DC-DC converter set at 15 volts.

Polar alignment:
The polar scope reticule is marked through 2030. Its appearance and use are well described in the Losmandy web pages. Using the polar scope with the legs of the mount fully retracted could be a literal pain in the neck for some people, because of the need to crouch and hold the neck in a particular position. I am not sure, though, that I am thrilled by the design of the polarscope illuminator. Pushing the button cycles the illumination through varying levels of intensity and whether it is steady or blinking. It turns off automatically after 2 minutes. I would probably prefer the usual style of illuminator that one could turn on or off manually and control the level of illumination with a switch.

Gemini 2:
At its inception it was rightfully excoriated because it was an unfulfilled promise, lacking any features, turning early purchasers into unwitting beta testers. That was then. Now it has all the features that any ordinary user would want. Advanced users may have very specific needs not yet addressed, but I would not know about that.

I enjoy the large PDA-like screen. The touch buttons are clearly and intuitively labelled. The brightness can be varied and there is a night mode with variable brightness as well. Basic tasks such as setting time, time offset, location, mount type, etc are easily accomplished. The hand control itself is fairly large, but in a way that fits the hand well. The casing does not feel slick, and should not slip out of the grasp.

I had no difficulty whatsoever establishing a peer-to-peer network with my netpad. It went just as described in the Gemini 2 website. I had updated ASCOM and loaded the gemini.net ASCOM driver. There was no difficulty connecting with that and controlling the mount through ASCOM. I will probably use the Gemini hand control all the time, but it was necessary to know that the ASCOM connection worked.

Pointing Accuracy:
I have not attempted the Modelling described in the Gemini manual. The notion of calibrating on umpteen stars on the east side and another umpteen stars on the west side, sometimes with indifferent results has not appealed to me, given the very limited time I normally have outside; between rooftops and trees I have just a narrow segment of sky with which to play. I had read some postings describing good results after a simple sync on a bright star. This has actually been fairly satisfactory at the focal length that I will using most of the time. Syncing on Dubhe and slewing to M51 put the object near the center of the imaging chip.

This is the result of the very first goto to M51:

Centering it would have been just a simple button tap.

There was no problem connecting the Orion SSAG to Gemini thru the autoguiding (ST4) port. Calibration was also no problem, although it took more steps than I had been expecting. Only later did I realize that I was calibrating with the hand control set at Centering speed. I do not know if this made a difference. Declination guiding was very good throughout this night. This suggests that the polar alignment was fairly good. The corrections were brief, much less than the 500ms that I had set. On my other mount I needed much longer pulses, sometimes as long as 1500ms to persuade DEC to move. RA was rather more troublesome, needing correction more often than DEC, with some fairly large movements. Loading the PHD logs into PHDLabs did confirm that DEC guiding error was about half the RA guding error. The stars were definitely eggy. I am not sure how much of the RA behavior is from the mount and how much was from my own foolishness: calibrating near Dubhe and imaging M51; forgetting to remove the 9x50 finderscope even though I had previously balanced the mount without it.

What started out as a testing getting-to-know-you session became an imaging session when I realized that the mount was running well and I did not wish to waste a relatively cool dark night. So I just let it run until I got too sleepy to continue.

Here is the image:

It is also the very first image that I have processed almost all the way through with PixInsight. I did import it into Photoshop to try some cosmetic surgery on the stars. It is quite a noisy image. Viewing the smaller images may be more merciful. To slightly misquote the great Mohammed Ali: I never claimed to be the greatest astrophotographer, just the most enthusiastic.

I am quite pleased with the mount. In spite of the initial hiccup it has already minimized my DEC frustrations. Getting to keep ALL of my 5-minutes subs is something that has never happened before. This is probably not a turnkey mount for the absolute tyro. However, it is a tuneable instrument and once the initial intimidation wears off, one should be able to adjust it to obtain the optimal performance.


#2 Hilmi


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Posted 22 April 2013 - 11:43 PM

I'm glad you are having a good time with your mount. It is great once you finally tune out all the bugs. The RA tracking drove me nuts for a full year till I realized I had a damaged worm gear. Some people also claim there is a batch of bad worm gears. Here are the things you can try:

1) Your guide settings might not be optimized, PHD does a good job on its own. MaximDL requires you know what you are doing.
2) Your gear mesh spacing might need adjustment, I'm not sure how to explain it, but there is some good material out there.
3)Try swapping out the Dec and RA worm gear.
4)Try getting a new worm gear if you have tried everything else, Scott is a great guy and would gladly cover it under warranty. (He doesn't communicate very well though, he will keep quiet and then suddenly in the mail you will find he sent you an upgrade, not just a replacement)
4) Sacrifice a chicken. The chicken has to have been brought up in an organic way. The sacrifice usually takes the form of a roast chicken and a family dinner where you spend time away from the scope.

#3 nganga


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Posted 23 April 2013 - 06:14 PM


Thanks for your responses. I suppose that it would be easy to tell if the gearbox is loose simply by trying to move it? I have just looked at the OPWB. Which screws would one unfasten to take the cover off? There are 2 large screws at the back, 2 screws in front aligned with the large screws at the back and one screw underneath. Is it possible to just remove the cover without messing with the gearbox and the coupling? Also would it be possible to just take off the gearbox cover without touching the coupling?


#4 Bart



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Posted 24 April 2013 - 10:02 AM

I still hope for a user manual someday.........

#5 vorkus


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Posted 24 April 2013 - 10:43 PM

Nice review. I'm in the same place you are. i recently got a new G11. I noticed while polar aligning with EQAlign that the RA drive seems to be fast. Not sure why. I had a less than successful first imaging night with it at 800mm. I have the OPW. I will try resetting Phd and see if I can work out the problem. I've been happy so far with the Gemini 2. I haven't tried the PEC. I also haven't done a 6 star alignment. I can do a 1 star alignment with my Atlas and it gets the target close to center. I haven't been so lucky with the G11. With the Atlas I can eyeball the RA and use Phd to put Polaris where it should be. Rarely do I find my first star out of the FOV. So far the G11 hasn't been close.

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