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Atlas EQ G compared to Celestron CG5 Advanced ?

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#26 Moromete


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Posted 08 October 2013 - 03:25 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.



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?

#27 David Pavlich

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Posted 08 October 2013 - 08:26 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.


#28 mdelling


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Posted 13 October 2013 - 08:51 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?


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