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Equipment Discussions >> Mounts

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: David Pavlich]
      #6123926 - 10/08/13 12:25 AM

Happy B-Day, David.

- Jim


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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: David Pavlich]
      #6123948 - 10/08/13 12:43 AM

Quote:

Quote:

Quote:

Well, I just came in from my C102's first light. Nice little refractor! But the real reason for the post is to reinforce just how good the ole' CG5 is. I plopped it in the backyard pointing it where I thought north would be. The first alignment star, Arcturus, wasn't even close. No surprise. The second star, Vega was closer but still out of the FOV. First Cal star was close, but out of the FOV. The second cal star was dead center! The third and fourth were centered and it was off to the races.

First object was M31. There it was, so I thought I'd see how well it would do on the other side of the meridian. I punched up M13 and it was centered.

Not bad for just putting it in a spot and doing an alignment. A good mount, that one!

David




David,

Do you have at least the same level of GOTO precision with the Atlas Eq G on both parts of the meridian after callibrating with only 2 or 3 stars and only pointing to north(not even using the polar scope)?




My first GEM was an Atlas and while the alignment in that hand controller only allowed for 3 stars, the gotos were alway good. But it was only good if I used all three stars. The third star corrected for cone error and that's important.

Where Celestron's hand controller wins the day is the All Star Polar Alignment routine.

David




Thank you David for your opinion.

Help me better understand please. You are saying that the GOTOs of an Atlas EQ G aligned on 3 stars are as good as those of a CG5GT aligned on 2+2 stars(or 2+4) even with a rough polar alignment of both mounts?

Than why doesn't one have the same GOTO precision with CG5GT after callibrating with only 2+1 stars, the other 3 stars becoming redundant somehow?


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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: Moromete]
      #6124056 - 10/08/13 02:44 AM

I wouldn't say redundant. Allow me to back up just a little. When I had the Atlas, I would actually use the polar scope to get it lined up quite close to where the mount should be pointed before I started the alignment. This helped putting the first alignment star into the FOV. From there, the remaining alignment stars were very close to being centered.

With the CG5, I don't bother even getting close to a polar alignment before I started. In this case, it does take an extra star or two to ensure that the mount is aligned properly. My guess is that if I were to actually look through the polar scope and do a polar alignment like I used to do with the Atlas, the stars beyond the first two alignment stars and the first cal star would probably be redundant.

Having said that, it takes little time to add all 4 cal stars and ensures that the pointing model is quite accurate.

David


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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: jrbarnett]
      #6124057 - 10/08/13 02:44 AM

Quote:

Happy B-Day, David.

- Jim




Thanks, Jim!!

David


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: rmollise]
      #6124062 - 10/08/13 02:53 AM

Rod, that may be generally true if you have a short refractor there or a C8 at most.

However an M10 on an Atlas imaging at native FL? I have no doubt it can be done, but it's not something I'd wish on my worst enemies... I am losing enough hair as it is.

I would actually put more money on a C11 on an Atlas, simply because it weighs less than the M10. Although a C9.25 or C8 would be a much better choice on weight grounds alone.


Quote:

And yet...and yet... Many Atlas users are taking images that are easily the equal of those done by people who spent for much more expensive mounts. Ground truth? What still matters most is the man or woman behind the camera, not the mount's pedigree.

And, yes, a Meade 10 will do fine on the Atlas. Personally, I think a C8 is still a very good solution, however. Unless you are going after small targets, you get that generous field, and the OTA will not stress your mount whether it is an EQ-6 or a G11 or a shake-your-money-maker.




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Moromete
professor emeritus


Reged: 02/15/12

Loc: Romania
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: David Pavlich]
      #6124123 - 10/08/13 04:25 AM

Quote:

I wouldn't say redundant. Allow me to back up just a little. When I had the Atlas, I would actually use the polar scope to get it lined up quite close to where the mount should be pointed before I started the alignment. This helped putting the first alignment star into the FOV. From there, the remaining alignment stars were very close to being centered.

With the CG5, I don't bother even getting close to a polar alignment before I started. In this case, it does take an extra star or two to ensure that the mount is aligned properly. My guess is that if I were to actually look through the polar scope and do a polar alignment like I used to do with the Atlas, the stars beyond the first two alignment stars and the first cal star would probably be redundant.

Having said that, it takes little time to add all 4 cal stars and ensures that the pointing model is quite accurate.

David




David,

First, Happy B-Day!

I think I understood quite well what you said. Thanks for taking the time to explain.

I have a CG5-GT and I totally agree with you that this mount doesn't need at all a reasonable polar alignment for very good GOTOs. With a bad polar alignment I noticed like you that after a minimum 2+2 stars alignment the GOTOs become great and 2+1 stars alignment is not enough for this. So I concluded that Celestron software modelling is not based on a good polar alignment for very good GOTOs and that's why it needs more callibration stars than 1.

On the other hand, I understood from you that Atlas EQ-G needs a quite good polar alignment using the polar scope (big difference versus CG5-GT here) because Orion software modelling is based on a good initial polar alignment in order to have good GOTOs after 2+1 stars alignment. That's why the first alignment star (and the other 2) lands in the FOV with Atlas EQ-G, contrary to CG5-GT. Right?

Regarding ASPA, I find it very good with CG5-GT if a careful 2+4 stars alignment was done before it. With Orion, I read ASPA is still imprecise with the latest firmware 3.35.


Now considering both CG5-GT and Atlas EQ-G were well aligned with 2+2 stars for Celestron, respectively 2+1 stars for Orion, and a good polar scope alignment was done for both, have you noticed any difference in GOTOs accuracy on both sides of the meridian between these 2 mounts at ~100x or more?


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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: Moromete]
      #6124408 - 10/08/13 09:26 AM

Thanks for the birthday wishes! What I consider a good polar alignment for visual is using the Atlas polar scope as prescribed and that's it. Nothing fancy like a drift or iterative methods. In my experience, the Atlas gotos were good after doing a proper star alignment and that was on both sides of the meridian.

My rave about the performance of the CG5 is due to the fact that you can find a good used one for about $450. And the fact that it's simple to use and has a decent visual loading.

Now, if imaging is in the equation, then the Atlas is a better choice. It's just a more stable platform. And it has the EQMOD option.

David


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mdelling
journeyman


Reged: 04/20/12

Re: Atlas EQ G compared to Celestron CG5 Advanced ? new [Re: David Pavlich]
      #6135916 - 10/13/13 09:51 PM

I'm using a C6-R on a CG5 and was thinking about upgrading the mount, not for imaging, I'm just not completely satisfied with the scopes stability. Anyway, what about the Sirius as a step up from the CG-5? Is that reasonable or not enough better to warrant to cost?

Thanks,


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