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Equipment Discussions >> Mounts

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PaulEK
professor emeritus
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Reged: 05/25/08

Loc: Wisconsin
G-11 with Gemini question
      #5506254 - 11/06/12 01:26 AM

I'll get to the question in a bit, but here's the background: I hope to purchase a G-11 soon, and really don't have a need or desire for go-to. I have an Orion Atlas, and used to have a Losmandy GM 100. I really loved the push-to possible with the GM-100, and don't like the necessity of unlocking and re-locking the clutches on the Atlas to hand slew to a target. (I almost never use the go-to on the Atlas.) I know this is not everyone's way of doing things, but it's what I prefer, and it would be much easier to just push to where I want to go than go through the hassle that the Atlas requires. It's one of the major attractions of the upgrade to the G-11.

Here's my question: If I DID buy a G-11 with Gemini (to use for outreach, or if I ever change my mind), is it still possible to simply push to where I want to go? I've read a lot about the mount, and know that the digital drive system allows this, but have not read whether the Gemini set-up does. Also, if it IS possible to push-to with Gemini, can the Gemini be used as a kind of digital setting circles substitute? I'll be buying the mount used, so it would be Gemini 1, not 2.

I apologize if these questions have been asked many times before; I haven't found anything on them. And if the questions seem ignorant to those in the know, it's because that's what I am on this subject!


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: G-11 with Gemini question new [Re: PaulEK]
      #5506286 - 11/06/12 02:23 AM

the Gemini 1 and 2 both have encoder inputs. But Losmandy no longer makes the encoder mounts for the G11. If you could find a used encoder-equipped G11 (most likely with digital drive) you could bolt on a Gemini and get the best of both.

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Kaizu
sage


Reged: 08/17/07

Loc: Finland
Re: G-11 with Gemini question new [Re: orlyandico]
      #5506302 - 11/06/12 03:03 AM

Have you checked ArgoNavis digital setting circles. They are availlable for G-11 but also for several other mounts.

Kaizu

Edited by Kaizu (11/06/12 03:04 AM)


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Cotts
Just Wondering
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Reged: 10/10/05

Loc: Toronto, Ontario
Re: G-11 with Gemini question new [Re: PaulEK]
      #5506537 - 11/06/12 09:30 AM

If you 'push to' with the Gemini, you will lose your pointing model. The encoders for Gemini are integral to the motors. If you move the telescope without using the motors the Gemini 'brain' will not know what you have done and will assume you're still at the last object you slewed to. This will not bode well for your next go-to slew.......

Dave


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D_talley
Carpal Tunnel
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Reged: 07/07/05

Loc: Richmond VA
Re: G-11 with Gemini question new [Re: Kaizu]
      #5506680 - 11/06/12 11:02 AM

Quote:

Have you checked ArgoNavis digital setting circles. They are availlable for G-11 but also for several other mounts.

Kaizu




The problem is they are no longer producing the encoder hardware for the G11 mount that you would need for the Argo Navis. You might pick up some for sale used but they are picked up quickly.


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: G-11 with Gemini question new [Re: D_talley]
      #5506901 - 11/06/12 01:21 PM

If you can't find any encoders right away, you can pushto a bright star and sync on it get your GOTO back after your pushto exploration.

Gale


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Startraffic
professor emeritus
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: G-11 with Gemini question new [Re: PaulEK]
      #5507098 - 11/06/12 03:39 PM

Paul,
I have a G11 that has gone from the Digital Drive System, to a Sky Commander with encoders, to Gemini-2. Gemini-1 supports external encoders, Gemini-2 does not support external encoders yet, but that support is planned. Finding original Losmandy encoders will be hard, they aren't made anymore & used ones haven't lost their value ~$350/set. Your 3rd party choices are JMI, Argo Navis, Sky Commander, & possibly others.
If you move the Gemini by hand without the encoders then Gemini will no longer know where it's pointing so you lose your ability to goto anything until you resync the mount. A pain, but a doing a goto is why you got Gemini in the 1st place, right?
I also do outreach with the BSA. The boys always seem to put their hands on the OTA and move it. With the SC-4 I'd just move it back on target & it would pick up tracking again. Gemini-1 will move it back on target & track from there if you have external encoders. With the Gemini-2, I have to redo the Goto, recenter & resync. If the OTA has been seriously moved it can take awhile. 6-11 yo boys don't have that long an attention span. HTH

Clear Dark Skies
Startraffic
39.138274 -77.168898
Alt 518ft ASL


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PaulEK
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Reged: 05/25/08

Loc: Wisconsin
Re: G-11 with Gemini question new [Re: Startraffic]
      #5509249 - 11/08/12 12:09 AM

Thanks for all the helpful information! One thing I really like about the G-11 is that it comes with decent, old-fashioned 'analog' setting circles. I could also just use them with the digital drive.

But knowing what you've given me will be a big help when I get the funds together (hopefully in the next few weeks). I'm just about finished with the Jaegers 6-inch f/10 scope. The tube and dew shield are at the powder-coater right now. I had the cell and focuser made by Crawford Machining, and they are rock solid, but also heavy. The Atlas holds the scope, but it's pretty wobbly.


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: G-11 with Gemini question new [Re: PaulEK]
      #5509613 - 11/08/12 09:50 AM

JMI does make hardware for encoders. but they don't look too great compared to the Losmandy stuff..

another (albeit significantly pricier) option is an old AP QMD mount (either a 600 or a 900). they look gorgeous with their encoders on.

downside.. no factory GoTo. i converted my AP600 to GoTo with a German controller, it supports the stock encoders so after de-clutching and moving the scope, it's a single button press to re-sync the controller to the encoders.


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Startraffic
professor emeritus
*****

Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: G-11 with Gemini question new [Re: orlyandico]
      #5509890 - 11/08/12 12:30 PM

orlyandico,
When I got my, Russell told me that mine were the last ones on the shelf, & they wouldn't be making any more. The sales dropped off significantly when Gemini-1 came out. A shame, since G-1 supports external encoders & G-2 is supposed to as soon as the code is written. I'm off my G11 now & on an HGM-200 (The Titans' older brother). The HGM has externals built into the mount & I'd like to use them. I do outreach with younger kids & they always put their hand on the OTA & give it a little push. Encoders would make correcting the targeting easy.

Clear Dark Skies
Startraffic
39.138274 -77.168898
Alt 518ft ASL


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pfile
Post Laureate


Reged: 06/14/09

Re: G-11 with Gemini question new [Re: Startraffic]
      #5512332 - 11/09/12 09:19 PM

Quote:

A shame, since G-1 supports external encoders & G-2 is supposed to as soon as the code is written.




do you have any more information on this? i've never seen mention of it on either the Losmandy Yahoo group or the gemini-2 yahoo group.

would the encoders just be for pointing information, or will gemini-2 support high resolution encoders and RA tick management?

thanks


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Startraffic
professor emeritus
*****

Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: G-11 with Gemini question new [Re: pfile]
      #5516549 - 11/12/12 07:14 PM

Pfile,
The Gemini-1 reference is http://gemini-2.com/downloads/pdf/GeminiL4UserManual.pdf page 10. For the Gemini-2 the reference for the encoder support http://gemini-2.com/Gemini2_features.php Port E Rene' has not written the code for this feature yet. I BELIEVE that they will have the same support as in Gemini-1. Pointing accuracy & high res functions , but that is my BELIEF & not guaranteed. I'm really hoping that is is both. I now have an HGM-200 that has built in high-res encoders & I'd like to use them with the G2. I do outreach with the BSA and Cubscouts invariably put their and on the OTA & move it off target. Gemini-1 would recognize this & reposition it back on target. I had a Sky Commander on my G11 & it would tell me when it was off target & in what direction so I could manually move it back on target. When I upgraded from the SC to Gemini-2 I lost that. I got the HGM with Gemini-1 & have swapped my G2 over to it & I've put the G1 on the G11. The G11 with the encoders is a great combo, I wish I could justify keeping it to SWMBO. However I can't so It'll be up on CN or Amart fairly soon.

Clear Dark Skies
Startraffic
39.138274 -77.168898
Alt 518ft ASL


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