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Equipment Discussions >> Mounts

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bunyon
Post Laureate
*****

Reged: 10/23/10

Loc: Winston-Salem, NC
mount option
      #5446655 - 09/29/12 11:45 AM

I have a CG5AT which has worked well. I can put a C8 on it and, so long as my polar alignmnent is dead on, can take 3 minute subs.

But the alignment must be dead on because it simply will not autoguide in declination. Backlash, box rubbing up against the knob, etc.

So, if I'm happy with weight of my kit on the CG5 but wanted a mount that could move better in declination and autoguide in declination, what should I look at?

Orion Sirius? Atlas? CGEM? Something I'm not thinking about?

Thanks.


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A. Viegas
Pooh-Bah
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Reged: 03/05/12

Loc: New York City/ CT
Re: mount option new [Re: bunyon]
      #5446979 - 09/29/12 03:19 PM

Paul,

I am a relative newbie at auto guiding, but if you are using PHD does it perform the calibration in Dec? Are you using a GPSUSB and can you check the Dec in the GPSCheck program to confirm your st4 cable is functional? If you are well polar aligned, the autoguider will mostly never need to use Dec anyhow, so maybe it's that reason? When you say it's rubbing, have you tried the other side of the meridian or just a target where the motor box does not touch the mount itself?

Al


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bunyon
Post Laureate
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Reged: 10/23/10

Loc: Winston-Salem, NC
Re: mount option new [Re: A. Viegas]
      #5447130 - 09/29/12 05:17 PM

PHD works but the backlash won't let it do so smoothly. So, the first few adjustmnets do nothing, then the next moves it 20 arc minutes. I've "solved" the problem by shooting wider field and getting the alignmnet so good there is no noticeable drift in Dec. Essentially, I'm using the autoguider as PEC.

Would like a better method but it's what I've got.


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A. Viegas
Pooh-Bah
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Reged: 03/05/12

Loc: New York City/ CT
Re: mount option new [Re: bunyon]
      #5447143 - 09/29/12 05:27 PM

unfortunately the CG5 is very much an introductory mount... If you are imaging at very long focal length then I think even a CGEM may not be adequate. However, if you try imaging at short 600-900mm I think you should be able to do relatively long subs. A week ago there was a post on this board showcasing a 25 minute sub on an unmodded CG5 of the western veil which was expertly done. So It's definitely doable at lower FL

Al


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Phil Sherman
Pooh-Bah


Reged: 12/07/10

Loc: Cleveland, Ohio
Re: mount option new [Re: A. Viegas]
      #5449919 - 10/01/12 10:22 AM

Don't get a Sirius. Your scope will be pushing it to its limits for AP. Try the Atlas instead. Get the ASCOM platform, EQMOD, PhD, and CdC and you;ll have a full set of free software to run the mount. CdC will also use the HGS (Hubble Guide Star) catalog if you need to see faint stars in your planetarium program.

Phil


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gustavo_sanchez
sage


Reged: 12/30/10

Loc: Puerto Rico, US
Re: mount option new [Re: Phil Sherman]
      #5451126 - 10/01/12 11:37 PM

Quote:

Don't get a Sirius. Your scope will be pushing it to its limits for AP. Try the Atlas instead. Get the ASCOM platform, EQMOD, PhD, and CdC and you;ll have a full set of free software to run the mount. CdC will also use the HGS (Hubble Guide Star) catalog if you need to see faint stars in your planetarium program.

Phil




Why the Sirius cannot handle a C8? The weight capacity of the mount is 30lbs, and the C8 is just 12.5 pounds. Adding a camera and a small guide scope should not add too much weight. I would not recommend shooting unguided at f/10,but with guiding I think the mount can handle the job very well.


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: mount option new [Re: gustavo_sanchez]
      #5451636 - 10/02/12 10:25 AM

Unless you have a size/wieght constraint, for the cost, I would recommend the Atlas or CGEM over the Sirius. The Atlas or CGEM will handle the CGE without even thinking about it whereas the Sirius will be in the upper half of the wieght range. The basic design of the Atlas/CGEM, while similar to the Sirius, is better.

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bunyon
Post Laureate
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Reged: 10/23/10

Loc: Winston-Salem, NC
Re: mount option new [Re: EFT]
      #5451676 - 10/02/12 10:49 AM

Thanks all. I'm not sure what you mean "for the cost", Ed. The Sirius is a good bit cheaper than either the Atlas or the CGEM.

I see the mount about a sturdier mount is better.

But, right now, the CG5 handles what I put on it fine - the Dec problem is there even when all I have on the mount is an ST80 and camera (with finder guider). I have gotten good images, retaining 90% of my subs, with the C8 at f/10 so long as my alignment is good enough to not drift in Dec.

Also, I don't have a permanent setup, so I have to move the mount out of the garage with each use and then align. So, heavier isn't necessarily better. I'm open to the idea that the Sirius isn't good enough but I'm not clear that a C8, finder/guider (at f/6.3) and camera is too much for it.

But, if it is Atlas or CGEM, which? I read enough stories about the CGEM to be cautious, but I know the Celestron systems and have plates, etc. for it. And stories can be misleading.


Thanks again.


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: mount option new [Re: bunyon]
      #5451702 - 10/02/12 11:02 AM

The Sirius is only $300 less than the Atlas/CGEM. That's actually quite a bit for a mount that is only about half way in between a CG-5 and an Atlas/CGEM. There is definitely a size and weight difference between the Sirius and the Atlas/CGEM but the Sirius is surprisingly heavy compared to a CG-5. I am not a fan of the Sirius tripod at all. I think that the CG-5 tripod is better.

My personal preference is for the CGEM due to the Nexstar hand controller and to the physical improvements made to the mount compared to the Atlas. Being familiar with the Nexstar, you would find the CGEM much easier to use right off the bat, but you would adjust to the Synscan or EQMOD without too much trouble. There are a lot of opinions between the two mounts, but I would say that overall it is fairly well split.


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bunyon
Post Laureate
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Reged: 10/23/10

Loc: Winston-Salem, NC
Re: mount option new [Re: EFT]
      #5451718 - 10/02/12 11:14 AM

Cool. I see your point. I was figuring CG-5:Sirius:CGEM to be about $300 increments but that was rounding error, I think.

Thanks, Ed.


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