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Equipment Discussions >> Mounts

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David R.
Vendor-Astrofactors
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Reged: 05/08/10

Loc: Plano, TX
NexStar 8SE Mount / GEM Upgrade Questions
      #3809332 - 05/16/10 07:31 PM

I have owned a Celestron 8SE for about a year now, and I am looking to further expand my AP capabilities.

If in the process of upgrading, I expand my DSO visual capabilities - great!

The reason I am posting here in "Mounts," is that I feel that I am most torn between ditching my whole setup for one of the following options:

  • (a) CPC1100 + Wedge
  • (b) OTA from my 8SE + GEM (is this possible?)
  • (c) 11" EdgeHD (or other 11" OTA) + GEM


Option 'a' certainly seems like the nice option from an "ease of visual" observation standpoint. But I am not sold that the wedge is as good as the GEM from a AP standpoint...is there any quantifiable difference between a wedge and a true GEM?

Option 'b' is appealing if I put my money towards a really nice mount and I can keep the 8SE light tripod for quick viewing. I've heard that the best telescope is the one you use However, I am still a bit of a newbie, and I don't want to get in over my head with too "custom" of a setup.

Option 'c' is appealing because I think it gives me portability + imaging on one platform. However, I sometimes think that I am just telling myself that it is portable...I'm obviously comfortable with < 30 lb setup that the 8SE currently offers, and I think that either 11" option start creeping towards the > 70 lb range.

Overall, it seems like some people think that GEMs put you in an uncomfortable viewing position. What exactly is uncomfortable?

And I've also been reading about this EQMOD solution for the Orion based GEMs (such as the Atlas.) Is EQMOD better than what Celestron bundles?


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RTLR 12
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Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: David R.]
      #3809639 - 05/16/10 10:39 PM

David,

I started out with an 8SE and then purchased a CG-5 Celestron mount. It is quite a change from the SE mount as far as stability (it's a lot more stable than the SE) and portability (the CG-5 is not as 'Grab & Go' as the SE). It was the right step for me as far as progression into more serious veiwing and also AP. There is more to learn of course, but not a hard transition. I am glad I did the move to the CG-5. I have now made the move from the CG-5 to a CGEM and I don't regret using the CG-5 as a stepping stone. The CGEM is twice the mount the CG-5 is, but I did learn a lot from the CG-5 as far as what direction I wanted to go with AP. As far as the awkward viewing positions incorporated with GEM use...all you need is a good viewing chair and you'll be more than comfortable. Also by staying with Celestron mounts the control systems are all the same and one less thing to have to learn anew.

Stan

PS:the next purchase for me is a EDGE 11 HD.


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Tiny
scholastic sledgehammer


Reged: 05/02/08

Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: RTLR 12]
      #3809687 - 05/16/10 11:06 PM

If you're going to get serious about imaging starting with a high F/L scope, such as the C11HD, is absolutely the wrong way to go especially since there is no proper focal reducer for any of those scopes yet to help. There is Fastar and Hyperstar but leaping into either probably isnt the best idea and it will make the scope a dedicated imager since it removes the secondary. And then theres the problems with dew.

Small fast APOs are the best scopes for imaging, especially for imaging DSOs, because they're extremely forgiving.

How much planning have you actually done? The reason i ask is its a lot more complex then just plopping down a couple thousand for a scope. Will you use a guider? Are you going to be using a DSLR or CCD Camera? Have you budgeted for any software that you may want to use such as PS? Do you know the ins and outs of image processing?

If you're actually willing to spend 3-4 thousand for an imaging setup, i'd put the money toward a nice APO, a capable mount, and the rest of it toward whatever else you need to get started [camera, guider, guidescope [if needed], any further counterweight [if needed], software etc].

A couple of points. Yes an 8SE can be mounted to a GEM without much trouble.

A fork mount with a wedge works fine and people have had great results. The trickiest part is the setup.

A C11 with a GEM and everything else would be easily be pushing 100 lb. Something to keep in mind if 30 or 70lb is a lot to you right now. And while it can be done, many consider OTAs that big undermounted on a CGEM or EQ-G for dedicated AP work. Something more ideal would be the Losmandy G11 or CGE which both weigh and cost quite a bit more.

Celestron have a number of programs that can do the same thing as EQMOD.



However my suggestion again is research everything, when satisfied purchase a solid APO and everything else you need, and go from there. Continue to use your 8SE as a visual scope.


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David R.
Vendor-Astrofactors
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Reged: 05/08/10

Loc: Plano, TX
Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: Tiny]
      #3809828 - 05/17/10 12:43 AM

I'm in the process of planning now ;-)

I am still deciding between using a DSLR or a CCD. I do own a DSLR and PS. I currently own a Nikon D300, and I do a lot of photography. But I'm not crazy about the idea of modifying it. I've used a Canon on the back of my 8SE - and gotten ok results with planets ... but I definitely like the idea of having the whole setup run through a laptop. I'm actually also a software developer by trade...so there are some interesting aspects to that as well...

I've been looking at the mono CCDs - I like the idea of doing multi-pass color stacking with filters. Also, it seems like you have to attach some sort of cooling either route (DSLR or CCD) and it seems like there are better off the shelf CCD solutions for AP.

I do think I want to use an auto-guider. That seems to be a nice way of long running exposures throughout an evening, and it seems like a way to compensate for less than perfect tracking from the mount itself.

The other thing I'm debating is whether or not I will get suitable results from urban skies or not. I have not made it out to any dark skies yet, and I am starting to think I need to just setup an observatory (like the POD.) If I do that, then I don't think that the C11 would be too big...

I haven't ever really thought about an APO. Maybe I suffer from aperture obsession

As far as using my 8SE as my visual scope, I'm pretty sure that I don't think it will do anymore. The mount is just way to under-built for the 8" tube. Anytime the wind blows or I breathe...the scope moves...but I do think the optics are decent.

Thanks for all the advice...I will have to research the APO path as well now.


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David R.
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Reged: 05/08/10

Loc: Plano, TX
Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: RTLR 12]
      #3809834 - 05/17/10 12:46 AM

Thanks for the feedback - it sounds like you've thought through the same problems I have ;-)

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Tiny
scholastic sledgehammer


Reged: 05/02/08

Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: David R.]
      #3809886 - 05/17/10 01:56 AM

A bigger mirror is fantastic for everything but for AP the focal ratio is far more important than the mirrors physical diameter. An F4 or F5 APO will be much easier to handle than an F8 SCT and that doesnt take into account sky resolution, or rather the lack there of, or any tracking errors, which are far more noticable the longer the focal length is.

Spend some time wandering through the CCD/DLSR sections here and you'll see some absolutely incredible wide field images from APO users.

Yea i went through this same song and dance. But you dont have to take my word for anything, as pictures speak volumes as to what an APO can do. Heres an example of one of my favorites that someone posted here [name escapes me], i believe they were using a DSLR through a Tak FSQ-106 which is a mere ~4" of Aperture. Course it also helps that they have access to some of the best skies in the world on Mauna kea but all the same, it doesnt take much aperture to produce incredible images.



I'd also recommend you pick up "A Guide to Astrophotography with Digital SLR Cameras" by Jerry Lodriguss right away. Its on a disc and can be purchased direct or from Amazon. Well worth the money as it contains a wealth of knowledge. Puts a lot of books on the subject to shame.


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David R.
Vendor-Astrofactors
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Reged: 05/08/10

Loc: Plano, TX
Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: Tiny]
      #3810203 - 05/17/10 09:32 AM

Thanks so much for the help!

I am now developing option 'd'

  • (d) Reasonably priced GEM that will support the swapping of my 8SE and a nice APO for AP...


Now I just have to decided what APO + AP imaging equipment to purchase...

I will definitely pick up a copy of that book as well. That seems like a no-brainer.

Cheers,
Dave


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Doug76
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Reged: 12/05/07

Loc: Refractor Heaven
Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: David R.]
      #3810243 - 05/17/10 09:48 AM

Option B.
Yes, this is doable, and you can sink your money into a fine mount. I suggest the Orion Sirius EQ-G. It will easily carry the scope, and is highly recommended for AP use.
And a Celestron Focal Reducer/Corrector will bring down your scopes f/ratio from f/10 to f/6.3, making for a wider field and faster shots in AP.


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David R.
Vendor-Astrofactors
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Reged: 05/08/10

Loc: Plano, TX
Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: Doug76]
      #3810338 - 05/17/10 10:53 AM

any particular reason for the Sirius vs the Atlas besides cost difference?

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Doug76
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Reged: 12/05/07

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Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: David R.]
      #3810455 - 05/17/10 11:53 AM

Weight.
The two mounts use the same motors and software.


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David R.
Vendor-Astrofactors
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Reged: 05/08/10

Loc: Plano, TX
Re: NexStar 8SE Mount / GEM Upgrade Questions new [Re: Doug76]
      #3810959 - 05/17/10 04:15 PM

Ok - so I went ahead and ordered the Atlas since the weight difference doesn't bother me. I will now have to start looking at all of the other stuff I need to buy next ;-)

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