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Equipment Discussions >> Mounts

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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 [Re: MartinTreadgold]
      #5806827 - 04/18/13 02:26 PM Attachment (17 downloads)

and base plate of the tripod

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