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PUT A C14 ON A CGEM-DX ?

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21 replies to this topic

#1 rcol

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Posted 22 November 2020 - 02:50 AM

Having recently obtained an older, blue Celestron C14 for next to nothing, I started looking at mounts.
I already have a CGEM which I use for a refractor. A CGEM-DX is supposed to be uograded with a larger payload.

 

Could I reasonably expect to do deep sky, long exposure (e.g. 60-120 sec) GUIDED with tye C14 on such a mount?

 

Comments greatly apprediated

 

- R.



#2 MJB87

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Posted 22 November 2020 - 03:38 AM

Couple of things to think about. 

 

The C14 has a much longer focal length, which makes unguided imaging more complicated (probably) than your refractor. You will probably want to use a focal reducer, or maybe even a Hyperstar.

 

You may have to deal with mirror flop. One option here is to add a Crayford focuser for fine-tuning of focus and then lock the mirror.

 

You will possibly decide you need a beefier dovetail bar and tube rings to create a more stable mounting solution.

 

This is not just idle speculation. I've been there, albeit with a CGE Pro, and ultimately had to do all of the above.

 

All of these add weight. With your OTA, a focal reducer, a Moonlight or other Crayford focuser, mounting plate and rings, a finder scope, a camera, various cables, etc. you are easily pushing or even exceeding the capacity limits of the mount. That payload capacity (50lbs) isn't even what most experienced  observers would employ. For a Celestron mount they would limit the load to 50%-60% of stated capacity. You will be way over that.



#3 pyrasanth

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Posted 22 November 2020 - 05:51 AM

My standard high resolution telescope is the C14 Edge at the native focal length of F11 which is just shy of 4 metres. That is a lot of focal length to guide accurately.

 

The use of traditional guide scopes on a rail mounted on the C14 will probably struggle at that focal length to keep accurate tracking- the stars do a merry dance in the slightest breeze.

 

My mount is the Paramount MX+, the OTA is secured in Bisque rings and the telescope has an accurate polar alignment and T-point model has in excess of 500 points.

 

I guide using the innovations foresight ONAG for guiding in the near infra red. Your field of view is so small you really need to be guiding through the telescopes main optics.

 

I wish you luck- it can be done but don't underestimate how difficult it can be if everything is not rock solid rigid & steady.

 

This is my lastest m81 image, taken last night with my C14 system https://www.cloudyni...sonal-c14-edge/

 

Good luck.


Edited by pyrasanth, 22 November 2020 - 05:52 AM.


#4 pyrasanth

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Posted 22 November 2020 - 05:56 AM

The CGX-L would be a far better mount. I hated the CGEM-DX mount-I used it only a few times before it was sold. It had a mind of its own- would do weird jumps for no apparent reason & that was with the C11. In my opinion the mount is more important than the optics-that's why I use a Paramount which costs more than the OTA.


Edited by pyrasanth, 22 November 2020 - 05:57 AM.


#5 WadeH237

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Posted 22 November 2020 - 06:45 AM

Having recently obtained an older, blue Celestron C14 for next to nothing, I started looking at mounts.
I already have a CGEM which I use for a refractor. A CGEM-DX is supposed to be uograded with a larger payload.

 

Could I reasonably expect to do deep sky, long exposure (e.g. 60-120 sec) GUIDED with tye C14 on such a mount?

 

Comments greatly apprediated

 

- R.

In my opinion, a C14 is seriously pushing the limits for visual on a CGEM-DX.  I wouldn't even think about trying to do deep sky imaging with such a setup.



#6 RogeZ

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Posted 22 November 2020 - 08:02 AM

For visual it will barely work, for AP is impossible with that mount.
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#7 Huangdi

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Posted 22 November 2020 - 08:36 AM

That's an EQ6 equivalent, huh? I'd say you will (if you have enough counterweights) have fun observing (although you better not touch it for the sake of vibrations...

I have handled C14s before and I own an EQ6... I'd call a C11 ambitious but acceptable but the 14" really is pushing it. We have one mounted on a 10micron GM2000, that does it justice!

Planetary imaging surely will work nicely as well after 30+sec of settling time.

I would forget about DSO photography. Standard seeing usually doesn't really allow photography with a C14 anyway and if you could afford the giant sensor and pixel size ccd that's required, you'd also likely be able to afford a giant mount for that giant scope... :)

Edited by Huangdi, 22 November 2020 - 08:38 AM.


#8 alphatripleplus

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Posted 22 November 2020 - 08:55 AM

If you wanted to use a C14 in hyperstar mode, I would say it is going to be okay on that mount. However, at f/10 or f/6.3, I would not bank on success.



#9 bikerdib

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Posted 22 November 2020 - 09:35 AM

I bought the C14 and CGEM DX package when the DX first came out.  To answer your question... NO!

 

I was doing only visual and even for that I could tell the mount was really being pushed.


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#10 CHASLX200

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Posted 22 November 2020 - 09:39 AM

Even a G11 is not enough for my taste. More like a AP900 or Titan.


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#11 pyrasanth

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Posted 22 November 2020 - 09:51 AM

That's an EQ6 equivalent, huh? I'd say you will (if you have enough counterweights) have fun observing (although you better not touch it for the sake of vibrations...

I have handled C14s before and I own an EQ6... I'd call a C11 ambitious but acceptable but the 14" really is pushing it. We have one mounted on a 10micron GM2000, that does it justice!

Planetary imaging surely will work nicely as well after 30+sec of settling time.

I would forget about DSO photography. Standard seeing usually doesn't really allow photography with a C14 anyway and if you could afford the giant sensor and pixel size ccd that's required, you'd also likely be able to afford a giant mount for that giant scope... smile.gif

One of the great things about a democracy is that we get to respect everybodies opinions- even if we disagree.

 

Some of the points made in your post are just plain wrong. The forums are full of fabulous C14 images- here is an image that I took last night with my C14 https://www.cloudyni...sonal-c14-edge/ I think it proves your post wrong and in fabulous fashion.


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#12 MJB87

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Posted 22 November 2020 - 01:18 PM

Nice photo. But it apparently wasn't on a CGEM-DX, so I don't understand the relevance. And the MX+ is a higher quality mount with TWICE the rated payload capacity.  Again, I don't understand the relevance.

 

Clearly, on a good mount with good technique, a 14" Celestron SCT can generate good images. But that's not what this discussion is about.



#13 Hobby Astronomer

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Posted 22 November 2020 - 02:51 PM

CGEM-DX? I know this is a rated G forum but seriously you would be torturing yourself for no benefit. Just trying to look though an eyepiece might give your epilepsy with that set up.

 

HA



#14 pyrasanth

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Posted 22 November 2020 - 03:19 PM

Nice photo. But it apparently wasn't on a CGEM-DX, so I don't understand the relevance. And the MX+ is a higher quality mount with TWICE the rated payload capacity.  Again, I don't understand the relevance.

 

Clearly, on a good mount with good technique, a 14" Celestron SCT can generate good images. But that's not what this discussion is about.

If  you read your post it does not say that you are solely refering to a 14 on a CGEM-DX. The post implies that a C14 is no good for imaging- that is my bone of contention with your post however the world is too small to fight about that issue- If I've misconstrued what you said then I apologise.



#15 MJB87

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Posted 22 November 2020 - 03:35 PM

Please explain to me where I disparage the C14 as an imaging platform. I merely pointed out that the additional weight of various accessories puts it over the practical limit of a CGEM-DX.



#16 EFT

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Posted 23 November 2020 - 08:46 PM

Like many things in this hobby, there are always people that can do things that are out of reach and patience of most people.  So you can never say never, but a C14 on a CGEM DX is a bad joke when it comes to most long-exposure imaging unless you have a lot of patience, guide, and can live with subs under (possibility well under) 120 seconds. 



#17 pyrasanth

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Posted 24 November 2020 - 11:40 AM

Like many things in this hobby, there are always people that can do things that are out of reach and patience of most people.  So you can never say never, but a C14 on a CGEM DX is a bad joke when it comes to most long-exposure imaging unless you have a lot of patience, guide, and can live with subs under (possibility well under) 120 seconds. 

I agree however the C14 on a CGEM-DX was sold as a complete system- the blurb never admitted it would be bad at guided long duration imaging.

 

I had a C11 with the CGEM-DX many years ago and that combination for imaging was unworkable. The mount had a mind of its own and would jump for reasons unknown completely ruining any chance of long duration imaging. I imagine with the C14 I would have been a nervous wreck. A platform has to be stable before I trust my equipment to it and the CGEM-DX is perhaps more suited to visual with a 9.25".


Edited by pyrasanth, 24 November 2020 - 11:41 AM.


#18 EFT

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Posted 24 November 2020 - 12:05 PM

Unfortunately, package deals from the mass-production manufacturers tend to include scopes that are, at best, useable for visual observing.  Even then, the performance may be subpar.  In general, it is safe to assume that a mass-produced scope is rated for visual observing, not imaging, and the largest scopes that it can be purchased with are not suited for imaging other then planetary, solar, and lunar with relatively low winds.


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#19 WadeH237

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Posted 24 November 2020 - 04:36 PM

I agree however the C14 on a CGEM-DX was sold as a complete system- the blurb never admitted it would be bad at guided long duration imaging.

What?  The marketing materials never mentioned that their package was wildly optimistic?

 

I'm shocked!  Shocked!


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#20 pyrasanth

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Posted 24 November 2020 - 04:44 PM

What?  The marketing materials never mentioned that their package was wildly optimistic?

 

I'm shocked!  Shocked!

No they did not......it's called "being liberal with the truth"mad.gif



#21 mich_al

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Posted 24 November 2020 - 07:06 PM

No they did not......it's called "being liberal with the truth"mad.gif

Optomistic would be a better word choice here than liberal!


Edited by mich_al, 24 November 2020 - 07:06 PM.

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#22 pyrasanth

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Posted 24 November 2020 - 07:15 PM

Optomistic would be a better word choice here than liberal!

Brochure says "great images to be had...on a wing and a prayer with a choir of angels in the background"




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