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Equipment Discussions >> Mounts

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starbob1
Pooh-Bah


Reged: 03/11/07

Loc: IN
New VX or good used CGEM
      #5797962 - 04/14/13 08:43 AM

Looking for a mount to pier mount. Had a CGEM before' did fine with guiding for imaging and great for visual. Mostly with a Small Apo on it. But I need a new mount and the VX look like a neat mount at a great price. But pier mounting it could be a problem. One can get a CGEM pier adapter but no VX on the market. Can get a almost new cgem for $1100 or a brand new VX for $800 .Any ideas. Thanks

Edited by starbob1 (04/14/13 10:17 AM)


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: New VX or good used CGEM new [Re: starbob1]
      #5798017 - 04/14/13 09:45 AM

I have a feeling that not so many people are going to suport the cgem option, but i'd say it's a good option.
I got one issue once that i could resolve and the 'cogging' problem is not prominent most of the time.
However, a used cgem for $1100 is not a terrible deal, in my opinion.


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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: New VX or good used CGEM new [Re: dickbill]
      #5798031 - 04/14/13 09:59 AM

If the VX motors and control board ever become available for the cgem it will become a game changer. As of now it is a bit of a toss up.

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zawijava
scholastic sledgehammer
*****

Reged: 10/06/07

Loc: Wells, Maine 04090
Re: New VX or good used CGEM new [Re: starbob1]
      #5798085 - 04/14/13 10:53 AM

I don't see the lack of a commercially available pier adapter for the AVX as much of a problem. If you have a pier already I'm willing to bet if you posted pics of it here you'd get enough suggestions that you could get something made locally. I would think the AVX on a pier would be a great choice. I adapted my AVX to sit on my A-P Wood tripod and it's really quite stable. I plan on pier mounting [another] AVX eventually in a small observatory. So show us what you've got to work with

-Tim

Quote:

Looking for a mount to pier mount. Had a CGEM before' did fine with guiding for imaging and great for visual. Mostly with a Small Apo on it. But I need a new mount and the VX look like a neat mount at a great price. But pier mounting it could be a problem. One can get a CGEM pier adapter but no VX on the market. Can get a almost new cgem for $1100 or a brand new VX for $800 .Any ideas. Thanks




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starbob1
Pooh-Bah


Reged: 03/11/07

Loc: IN
Re: New VX or good used CGEM new [Re: zawijava]
      #5798157 - 04/14/13 11:44 AM

Yes Tim I agree' a pier adapter can be made somehow.
I really do not want another cgem'even though a good mount' many issue's can pop up. Plus I bet you the cgem will be discontinued and upgraded like the VX. The price of the VX is great. Reviews look good. I will only use a small refrator or 8in Edge at most so weight will not be a issue ' I already have a 12.5 dob in my observatory and that works great on DSO and planets. My pier uses two top plates of steel 10in by 10in. I already have one plate with the Vixen hub for a GP-D2 and another drilled for a CGE adapter and CGEM adapter from Starzonia. Will post some pier pics later. Thanks all Bob


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Dwight56
super member


Reged: 04/17/10

Re: New VX or good used CGEM new [Re: starbob1]
      #5798162 - 04/14/13 11:48 AM

Out of curiosity what are the dimensions of the RA and DEc gears on the VX mount I cannot seem to fine that info

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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: New VX or good used CGEM [Re: starbob1]
      #5800195 - 04/15/13 10:43 AM

It sounds as if you have made up your mind against the CGEM, however, if you are pier mounting, I don't know why you would not go with the larger mount with greater capacity and a proven track record. I would only choose the VX if portability was an issue.

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starbob1
Pooh-Bah


Reged: 03/11/07

Loc: IN
Re: New VX or good used CGEM [Re: EFT]
      #5800766 - 04/15/13 02:53 PM

Hi Ed' Your opion is highly valued. Your right why limit myself in the future. I really kind of want a Vixen GP-D2.Even though non goto it was a great mount. 3 min unguided were common. Just have to decide. Thanks Bob

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faltered
professor emeritus


Reged: 04/01/05

Re: New VX or good used CGEM [Re: starbob1]
      #5800974 - 04/15/13 04:42 PM

The CGEM had some issues out of the gate, but it sure seems that those issues have really subsided. Being a used one, and if you trust the seller - I would have no problem with the CGEM. And I would have total confidence in a new one. The CGEM is a great mount.

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ur7x
professor emeritus


Reged: 01/08/12

Re: New VX or good used CGEM [Re: faltered]
      #5801483 - 04/15/13 08:49 PM

Love both mounts, I would take the CGEM in a heart beat... But it is a heavy beast and not all that portable.

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Patrick
Postmaster
*****

Reged: 05/16/03

Loc: Franklin, Ohio
Re: New VX or good used CGEM [Re: starbob1]
      #5801757 - 04/15/13 11:22 PM

Quote:

ad a CGEM before' did fine with guiding for imaging and great for visual. Mostly with a Small Apo on it. But I need a new mount and the VX look like a neat mount at a great price. But pier mounting it could be a problem. One can get a CGEM pier adapter but no VX on the market. Can get a almost new cgem for $1100 or a brand new VX for $800 .Any ideas. Thanks





I think it really depends on how much weight you want to put on it. I've only seen the VX mount during the day and have never used one. However, I can tell you there is a substantial difference in the size when you look at one sitting next to a CGEM (the VX almost looks puny). But having owned several CG5's I can respect the VX's capabilities. Just make sure you size your instruments accordingly.

Patrick


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: New VX or good used CGEM [Re: Patrick]
      #5801951 - 04/16/13 03:18 AM

One point in favour of the AVX is that it has new motors, gearboxes and firmware that removes the non periodic error, and Dec cogging.

There's rumours that the CGEM will get these (possibly as an upgrade but no promises) but at the moment you may get better guiding and definitely better unguided PEC corrected tracking from the AVX. As long as you don't overload it.

Chris


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RTLR 12
Post Laureate
*****

Reged: 12/04/08

Loc: The Great Pacific NorthWest
Re: New VX or good used CGEM [Re: cn register 5]
      #5802397 - 04/16/13 11:45 AM

The firmware fix for motor cogging on the CGEM is in beta testing now. The reason this fix has taken so long is because it was not a wide spread problem and therefore was not a priority with Celestron.

Stan


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Patrick
Postmaster
*****

Reged: 05/16/03

Loc: Franklin, Ohio
Re: New VX or good used CGEM new [Re: RTLR 12]
      #5802817 - 04/16/13 02:13 PM

Quote:

The firmware fix for motor cogging on the CGEM is in beta testing now.




Good to know.

Quote:

The reason this fix has taken so long is because it was not a wide spread problem and therefore was not a priority with Celestron.




The way you hear it here on the forums, all CGEM's have been rendered as useless piles of junk due to this 'cogging' issue.

Patrick


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starbob1
Pooh-Bah


Reged: 03/11/07

Loc: IN
Re: New VX or good used CGEM new [Re: Patrick]
      #5802915 - 04/16/13 03:13 PM

I might try one of the new ioptron Q45 mounts instead of the CGEM again. Seems it would be easy to pier mount also.Bob

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dragonslayer1
Pooh-Bah


Reged: 02/25/12

Loc: SLC, UT
Re: New VX or good used CGEM new [Re: starbob1]
      #5803599 - 04/16/13 10:00 PM

If I recall correctly the payload for VX 30lbs, CG-5 35lbs, CGEM-DX 50lbs, and CGEM 40lbs. The VX is the least of all for carrying capacity from my understanding. Kasey

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Mike X.
scholastic sledgehammer


Reged: 06/28/10

Loc: Greece-Athens and Rome-Italy
Re: New VX or good used CGEM new [Re: dragonslayer1]
      #5803696 - 04/16/13 11:02 PM

Yes those are the stated payloads.
I find the CG5-GT payload of 35lbs unrealistic for astrophotography,which is what our friend wishes to do. Probably the VX may handle a little better the load than the CG5 due to the upgraded base that supports it but..again i have my doubts regarding AP if it is rated fot 35 lbs.
Personally i find the 25lbs a serious higher limit for the CG5 for guided AP, up to 1 meter. Best if under that.

Can't say anything about the CGEM and the DX, i never used them.

Edited by Mike X. (04/16/13 11:05 PM)


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orlyandico
Postmaster
*****

Reged: 08/10/09

Loc: Singapore
Re: New VX or good used CGEM new [Re: Mike X.]
      #5803872 - 04/17/13 02:24 AM

IMHO the cogging is not the worst issue. My CGEM has a really bad 8/3 that makes guiding it a challenge. I can get no better than 2" RMS periodic error (as reported by PHD) when guiding with 1-2 second exposures.

Needless to say, unguided imaging is out.

I have also seen the cogging and I imagine it is an issue because the DEC doesn't respond to corrections until they are way too large. But you can avoid DEC guiding by doing a very accurate polar alignment. And, there is a firmware fix available.

For the sole reason that you might get a CGEM with a large 8/3 like mine, I would go with the AVX.

Or wait for Celestron to release an updated CGEM with the AVX motors in it (that should eliminate the 8/3).


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: New VX or good used CGEM new [Re: orlyandico]
      #5803880 - 04/17/13 02:42 AM

Looking at the CG-5 and AVX side by side the AVX looks more capable of carrying a load so I think that Celestron may be being more realistic about the maximum load with it

If it's ever clear I'll try it with the 6" GSO RC with ST80 piggybacked. With the cameras filterwheel and focuser that must be getting close to the limit.

Chris


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stevecoe
"Astronomical Tourist"
*****

Reged: 04/24/04

Loc: Arizona, USA
Re: New VX or good used CGEM new [Re: cn register 5]
      #5803949 - 04/17/13 05:11 AM

Orly;

What is the "8/3"??

Steve Coe


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