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CPC 800 Edge and AVX mount for astrophotography?

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#1 jsnatale

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Posted 23 October 2021 - 03:28 AM

I currently have a CPC 800 Edge HD telescope with dual fork arms, an alt-az mount, GPS, and go-to capability. It is a good scope for visual astronomy, but I have become interested in astrophotography, and am considering selling it to get a CPC 800 Edge AVX. The CPC I have is not working well for astrophotography since the dual fork arm configuration doesn't allow vertical imaging (the imaging train hits the mount when scope is pointed vertically), and the alt-az mount in general isn't suitable for astrophotography. Before I buy I wanted to get your opinions on this set up (CPC 800 Edge w/AVX mount). Here is a link:

 

https://www.highpoin...telescope-12031

 

Here are some questions I have:

1. Is the CPC 800 Edge w/AVX mount generally a good set-up for both planetary and deep sky astrophotography? I would like both wide field views for deep sky objects, and also be able to capture good planetary detail.

2. Is the AVX mount capable of supporting the 8" OTA without causing any problems with tracking/alignment? The mount has a 30-lb capacity- is that adequate for carrying the weight of the OTA with no issues?

3. It doesn't have GPS- is that an issue? Should I instead consider other mounts with GPS? And are there other mounts that are in your opinion generally better overall than the AVX for this telescope - say a CEM or ioptron? If so which ones, and why?

4.How difficult is this telescope and mount to set up?  How much time does it take to align? Is the alignment process quick and easy? And does it track well, or need to be re-aligned often?

5. I am interested in deep sky, long exposure imaging. Do I need to get the optional polar alignment scope, or get a guide scope to ensure good alignment and tracking during imaging?

 

I am new to astrophotography, and could really use your opinions/feedback on this telescope and mount before I buy. Not sure if it is a good beginner's scope/mount for astrophotography, or if I should instead consider other options (i.e., maybe a refractor)?

 

Last, if any of you currently have the CPC 800 Edge w/AVX mount and have deep sky or planetary images you can attach, that would be appreciated as well.

 

EDIT: There are also a couple other equatorial mounts that Celestron offers: the CGEM II  and the CGX. Links to both are below. Would these be better choices than the AVX? Does anyone have experience with either of these?

 

 

https://www.highpoin...telescope-12017

 

 

https://www.highpoin...telescope-12055


Edited by jsnatale, 23 October 2021 - 07:57 AM.


#2 DirtyRod

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Posted 23 October 2021 - 03:48 AM

I've got an 8" SCT on an AVX and I've struggled to get consistent tracking. Tonight, for instance, I was on the Bubble Nebula and had consistent .5-.6 total RMS and then swung over to M42 and it's all over the place. I've tweaked and tried to tune and pretty much decided on a different mount for this OTA. Some folks can get them to work fine but I have not had the same luck with my 23lbs imaging setup on an AVX.

 

In terms of setup, it's no more difficult than any other mid level EQ mount. With the standard handset, you just have to enter the date and time and it remembers your location so a GPS was not necessary for me. I do like StarSense which allows you to hit Auto Align and you let it do it's thing. After that you do your All Star Polar align and then realign. Every time you set up you need to Align and Polar align no matter what EQ mount you get unless you leave it set up in the same spot. Once you get good, those two things take 5-10 mins. Since I can't see Polaris, I often have to do a polar alignment twice or I will do a drift alignment in the guiding software. 

 

The polar alignment scope and a guide scope are two different things. The polar alignment scope is to help you polar align when you set up. For long exposure stuff, you will need a guidescope or an Off Axis Guider plus the guide camera. That ensures your tracking is spot on. 

 

If the OTA is the same, why not just buy a new mount and tripod and then sell your mount? Not sure I would spend money buying the same OTA unless you don't think you can sell your mount by itself. Still may come out better in the long run.  


Edited by DirtyRod, 23 October 2021 - 04:11 AM.

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#3 GazingOli

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Posted 23 October 2021 - 04:28 AM

20210427_022151.jpg

 

why not use a wedge? I got a CPC800 as well and use it for EAA. With reducer I can easily do 60s subs without guiding. The CPC ist rock sturdy and the big wedge also very stable. Just heavy - 30 lbs the wedge alone.

 

CS.Oli


Edited by GazingOli, 23 October 2021 - 04:56 AM.

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#4 Rac19

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Posted 23 October 2021 - 04:30 AM

For what it's worth, a while ago I asked, on this forum,  if it was worth updating my Evolution with wedge to an AVX and the general opinion seemed to be don't bother. The recommendations were to consider a CGEM or, even better a CGX.

 

I have decided to see what I can achieve with the wedge.


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#5 GoFish

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Posted 23 October 2021 - 05:38 AM

No, that would not be a good choice for deep sky imaging. Instead, start with a small, fast refractor (60-80mm, f/6 or f/7). 
 

Place the financial emphasis on the mount, not the optics. There are many, many suitable mounts.  All are expensive. The AVX, while inexpensive and fine for visual, has a terrible reputation among serious imagers so probably one to avoid. 
 

Your CPC800 will be fine for planetary imaging, as-is. It would be too much (weight, mostly) for me to deal with a CPC800 on a wedge, but YMMV. I can only say that it is a relatively uncommon configuration for deep sky imaging. 


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#6 TelescopeGreg

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Posted 23 October 2021 - 03:22 PM

What Jim said.

 

The AVX (I have one) can be used for deep sky AP, but it's pretty limited.  You will absolutely need an autoguider with it (second scope, camera, computer), and even so, it has limits.  The long focal length of the 8" SCT magnifies not only the sky, but also any and all little wobbles that the mount imparts on the scope, and the AVX has a lot of them.  Keep the scope to somewhere around 500mm focal length, add an autoguider, and with some tuning, go for the AVX. 

 

My scope own is 910mm, and I have to be very careful in how I balance things to get good images without trailed stars.  Done right, I can do 5 minute exposures for hours on end, and keep pretty much all of them.  But that's the result of a couple of years of tweaking, critically including switching to a much lower profile scope (5" vs 8").  I used to have an 8" f/5 Newtonian on the mount, and had to toss 20% of the subs, even with the guider running (80% without).  You can't cheat on physics.

 

That said, if you're going after Planetary / Lunar imaging, that's a very different hobby.  Instead of taking long exposures (minutes), you're taking high speed movies (frames with sub-second exposures).  There you probably can use the scope and mount you already have.  Processing is with Autostakkert.

 

Don't forget that deep sky targets tend to be pretty large (Andromeda Galaxy is 3x wider than the full Moon), and incredibly dim.  You really don't want a long focal length, and you really need a fast scope.  Most DSO AP is done with scopes in the 500-750mm focal length range, and f/7 or faster.  The planets, on the other hand, are very small, and incredibly bright.  2,000mm and f/10 is usually Barlowed 2x or more for planetary imaging. 

 

So, if you're wanting to go after deep sky stuff, get an 80mm f/6 APO scope and that AVX (or an EQ6-R if you can instead - much better), and a 50mm f/4 guide scope, and go for it.  Keep the 8" SCT for the planets.

 

Edit:  To your questions...

 

1.  Not for deep sky, per the above.  Two different hobbies, with different equipment needed.

2.  No.  Guider needed, and then only with a much smaller scope.  Aim for 50% of that 30 lbs capacity.

3.  GPS is not needed.  Manually set the time and location.  AVX has a realtime clock.

4.  Pretty easy, with a little practice.  I can go from the garage to imaging in under 30 minutes. 

5.  You need to get a good polar alignment.  The polar scope that is offered for the AVX is not ideal, but it can work with some careful setup and practice.  I use one.  There are software tools that can use your imaging camera to assist with the final alignment. 


Edited by TelescopeGreg, 23 October 2021 - 03:29 PM.

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#7 jsnatale

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Posted 24 October 2021 - 07:01 AM

Thanks everyone. I am looking at other GEM options besides the AVX. Does anyone have knowledge of, or experience with the Celestron CGEM II or CGX mounts?  How about the ioptron CEM25P or Meade LX85?  From what I have heard, all of these seem to be capable of handling my CPC 800. 

 

In the future, I will hopefully also be getting a small refractor, but my first concern is getting the CPC on an equatorial mount.



#8 GoFish

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Posted 24 October 2021 - 07:43 AM

I can’t offer opinions on the mounts you’re looking at, but others will. My AP mounts are both SkyWatcher/Orion products (Sirius EQ-G, Atlas EQ-G). The Atlas would handle an 8” SCT for AP, but I doubt I would get good guiding results using the Sirius with that OTA.  I also have an AVX that is adequate with an 8” SCT at f/6.3 for EAA, but I doubt going longer than 30s exposures would bring much joy. 

 

My other comments:

  1. Deforking the CPC800 is not a trivial operation. Not horribly difficult, but not like just removing the OTA from a dovetail clamp. 
  2. Once this is done, the CPC fork mount will become an orphan.  You might be able to sell it, but I don’t think there would be much of a market.
  3. Starting AP using an 8” SCT is going to be a harsh introduction to the hobby.  The long focal length and “special” characteristics of SCT’s are famous for creating guiding challenges.  Conventional wisdom says you need to use an OAG for guiding. 

My approach to this situation would be different. I would either keep the CPC800 and buy a new mount and refractor, or sell the CPC800 intact and do the same. If budget constraints dictate, I’d buy a relatively inexpensive 70mm ED doublet refractor to keep costs down. But I would not scrimp on the new mount and I wouldn’t defork the CPC800.

 

 


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#9 DirtyRod

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Posted 24 October 2021 - 09:35 AM

Thanks everyone. I am looking at other GEM options besides the AVX. Does anyone have knowledge of, or experience with the Celestron CGEM II or CGX mounts?  How about the ioptron CEM25P or Meade LX85?  From what I have heard, all of these seem to be capable of handling my CPC 800. 

 

In the future, I will hopefully also be getting a small refractor, but my first concern is getting the CPC on an equatorial mount.

I've got a friend with the CGX and CGX-L mounts and they get good results with 11 and 14" SCTs. I've been researching my upgrade and pretty much settled on either the CGX or the EQ6R-Pro. I've seen lots of good results from those. 


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