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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
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 new [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 new [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 new [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
sage


Reged: 01/08/12

Re: New VX or good used CGEM new [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 new [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 new [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 new [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
scholastic sledgehammer


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
Post Laureate
*****

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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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: New VX or good used CGEM new [Re: stevecoe]
      #5803953 - 04/17/13 05:22 AM

Frankly, I would really love to test CGEM with cogging and "8/3" problem to compare results with my CGEM.

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RTLR 12
Post Laureate
*****

Reged: 12/04/08

Loc: The Great Pacific NorthWest
Re: New VX or good used CGEM new [Re: orlyandico]
      #5803957 - 04/17/13 05:30 AM

Have you tried guiding with a different program besides PHD?

Stan


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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: New VX or good used CGEM new [Re: stevecoe]
      #5804066 - 04/17/13 07:59 AM Attachment (32 downloads)

I just bought the new Celestron Advanced VX mount, and i took it on a weekend trip to Germany, and it was brilliant. The price is very reasonable, 750 Euros here. It's really easy to set up without any fuss. Its a big improvement on the CG-5 mount, and works equally as well as the CGEM mount. As the CGEM mount is bigger, it can handle more weight. The CGEM mount handles upto 40lbs whereas the AVX mount is 30lbs, so weight is the only thing you have to consider here. If you don't plan to use more than 30lbs, go for the VX mount, its newer with more up to date hardware.

See the photo attached of it nicely set up with a 5" Nexstar SCT


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FoxTrot
sage


Reged: 06/01/06

Loc: Melbourne, Australia
Re: New VX or good used CGEM new [Re: stevecoe]
      #5804135 - 04/17/13 08:59 AM

Steve, I think it has something to do with the 'integer gear' ratios designed into the VX drive, compared to the odd ratio (8/3) in the CGEM. An odd 'non-integer' ratio makes the drive more susceptible to periodic error I believe ? Fox

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FoxTrot
sage


Reged: 06/01/06

Loc: Melbourne, Australia
Re: New VX or good used CGEM new [Re: MartinTreadgold]
      #5804148 - 04/17/13 09:11 AM

Quote:

I just bought the new Celestron Advanced VX mount, and i took it on a weekend trip to Germany, and it was brilliant. The price is very reasonable, 750 Euros here. It's really easy to set up without any fuss. Its a big improvement on the CG-5 mount, and works equally as well as the CGEM mount. As the CGEM mount is bigger, it can handle more weight. The CGEM mount handles upto 40lbs whereas the AVX mount is 30lbs, so weight is the only thing you have to consider here. If you don't plan to use more than 30lbs, go for the VX mount, its newer with more up to date hardware.

See the photo attached of it nicely set up with a 5" Nexstar SCT



Martin, I have an LXD75 which I think is substandard for my NP127is (about 7.5 kg, or 16 lb or so). Do you think the AVX would be good with the NP127is? Does it really feel that much more substantial and stiffer than the CG-5?

The CGEM and Skywatcher AZ-EQ6 have caught my eye, but both these mounts are a lot heavier than the CG-5/AVX class mounts, and portability is an issue for me. Thanks, Fox


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Raginar
Post Laureate
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: New VX or good used CGEM new [Re: FoxTrot]
      #5804149 - 04/17/13 09:12 AM

Martin,

I used a C5 on my CGEM. Wonderful little telescopes with a great FOV.


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: New VX or good used CGEM new [Re: stevecoe]
      #5804295 - 04/17/13 10:37 AM

The 8/3 is a non-integer gearbox harmonic in the CGEM that is impossible to remove with periodic error correction.

On my CGEM the magnitude of the 8/3 is about 22 arc-seconds (even more than the worm fundamental of 16 arc-seconds). But on most CGEM's the 8/3 is only about 6 arc-seconds. So PEC on these mounts can reduce total PE from around 30" to 7" or 8".


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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: orlyandico]
      #5805305 - 04/17/13 07:24 PM

The azeq6 is a little lighter than the Cgem but it's still more than twice the weight of a cg5. It weights like an atlas more or less. Less than a kg lighter.
Personally I noticed great difference in stability in confront with my cg5 while it maintains portability.

Edited by Mike X. (04/17/13 07:25 PM)


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oo_void
professor emeritus


Reged: 11/13/09

Loc: San Francisco, CA
Re: New VX or good used CGEM new [Re: orlyandico]
      #5805308 - 04/17/13 07:25 PM

If you're guiding, you don't really need to use PEC (I've seen arguments ranging from it get in the way to it couldn't hurt, but not a must have). PEC is useful for unguided imaging, but expectation should be set appropriately, we're talking a $1.5k mount, not a $10k direct drive.

Bottom line is that the CGEM is a fine and robust mount for the money. Someone posted a few messages back about at AT6RC with an ST80 piggy-backed on a VX. That was the config that drove me to upgrade from a CG-5 to a CGEM. I found the highly centralized load to be just a bit too much for the CG-5 DEC access. In fact, I always had trouble with DEC corrections until I upgraded. That said, I have yet to use, or know anybody else directly who owns a VX.


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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: New VX or good used CGEM new [Re: Raginar]
      #5806100 - 04/18/13 05:38 AM

Quote:

Martin,

I used a C5 on my CGEM. Wonderful little telescopes with a great FOV.




I've ran out of money now.. but I plan to upgrade the OTA to an 8 inch SCT, or Edge HD...


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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: New VX or good used CGEM new [Re: FoxTrot]
      #5806110 - 04/18/13 05:52 AM

Quote:

Quote:

I just bought the new Celestron Advanced VX mount, and i took it on a weekend trip to Germany, and it was brilliant. The price is very reasonable, 750 Euros here. It's really easy to set up without any fuss. Its a big improvement on the CG-5 mount, and works equally as well as the CGEM mount. As the CGEM mount is bigger, it can handle more weight. The CGEM mount handles upto 40lbs whereas the AVX mount is 30lbs, so weight is the only thing you have to consider here. If you don't plan to use more than 30lbs, go for the VX mount, its newer with more up to date hardware.

See the photo attached of it nicely set up with a 5" Nexstar SCT



Martin, I have an LXD75 which I think is substandard for my NP127is (about 7.5 kg, or 16 lb or so). Do you think the AVX would be good with the NP127is? Does it really feel that much more substantial and stiffer than the CG-5?

The CGEM and Skywatcher AZ-EQ6 have caught my eye, but both these mounts are a lot heavier than the CG-5/AVX class mounts, and portability is an issue for me. Thanks, Fox




I'd say the AVX mount is still just about portable, not too heavy. The Tripod legs are really heavy duty, infact they are the same tripod legs as the NEQ6 just a different colour, NEQ6 is white, AVX black

The AVX holds upto 30lbs, whereas the CGEM mount is 40lbs according to the specs on celestrons website. (thats probably including the counterweight also)

If you have heavier than 30lbs optics in total, go for something more substantial such as the NEQ 6, but then you lose portability etc

If weight isn't an issue, sure, go for the VX mount. Celestron have made a great product. It feels really robust.

I've been reading a few review sites and a lot of people say this a great improvement on the CG-5 mount.

All my Astro buddies on last weekend's trip were pretty impressed with it, and they all have NEQ6 mounts.

So overall, when buying, you need to consider, the weight of your OTA, +weight of a DSLR camera, additional finder scopes, and other accessories... PLUS.. the weight of the counterweight = overall load on the mount.. and if all that exceeds 30lbs, you need a more heavy duty telescope than the AVX

Edited by MartinTreadgold (04/18/13 06:05 AM)


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FoxTrot
sage


Reged: 06/01/06

Loc: Melbourne, Australia
Re: New VX or good used CGEM new [Re: MartinTreadgold]
      #5806207 - 04/18/13 08:09 AM

Thanks Martin, Fox!

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starbob1
Pooh-Bah


Reged: 03/11/07

Loc: IN
Re: New VX or good used CGEM new [Re: FoxTrot]
      #5806220 - 04/18/13 08:18 AM

I think the 30lb linmit is for payload the buisness end' Not counterweight also.

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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: New VX or good used CGEM new [Re: starbob1]
      #5806822 - 04/18/13 02:22 PM Attachment (21 downloads)

here's some close ups of the mount


Edited by MartinTreadgold (04/18/13 02:24 PM)


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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: New VX or good used CGEM new [Re: MartinTreadgold]
      #5806827 - 04/18/13 02:26 PM Attachment (17 downloads)

and base plate of the tripod

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