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My Impressions of the C9.25

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#26 Procyon

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Posted 11 December 2016 - 02:29 AM

I just came from outside with the Edge 8. It took me 3 minutes to set everything back inside. It's so easy it makes me want to go outside every clear night. It took the Edge about 1h-1h15mins to show pin point stars across the entire fov. It was 15 Fahrenheit and seeing/transparency was average, maybe a little bit better.   



#27 rguasto

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Posted 11 December 2016 - 08:18 AM

Very interesting, but I'd still get an edge HD.
-Rob

#28 coopman

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Posted 11 December 2016 - 09:35 AM

Thanks for the very interesting report Bill.

#29 BillP

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Posted 11 December 2016 - 10:41 AM

I just came from outside with the Edge 8. It took me 3 minutes to set everything back inside. It's so easy it makes me want to go outside every clear night. It took the Edge about 1h-1h15mins to show pin point stars across the entire fov. It was 15 Fahrenheit and seeing/transparency was average, maybe a little bit better.   

 

IMO 8" is the sweet spot intersection for capability vs portability with SCTs and Dobs.  For Refractors I'd say it is probably the 120-130mm class.  And if someone is after a one scope solution these are best IMO because they have the broadest capability at a still modest aperture.  But like I said, for me 8" is a non-starter as I want something just a little larger without going the extra expense of the Edge or ACF design (and I personally feel quite an overpriced extra).


Edited by BillP, 11 December 2016 - 10:42 AM.


#30 Procyon

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Posted 11 December 2016 - 11:20 AM

It's too bad there's no 9.25" Edge Focal Reducer, otherwise I'd be tracking down a used 9.25 Edge. Maybe next year.


Edited by Procyon, 11 December 2016 - 11:20 AM.


#31 MrJones

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Posted 11 December 2016 - 07:56 PM

Nice to know the Paracorr can be used. I tried the GSO coma corrector with my C9.25 and couldn't get it to focus but I'm not sure what else I was using with it.

 

Also, agreed on the Airy pattern and C9.25. I easily saw the first ring many times with higher magnification chasing double stars. Mine was an especially nice USA gray tube.



#32 jrbarnett

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Posted 11 December 2016 - 08:16 PM



I am surprised that a C9.25 on the necessary mount would be easier to set up than a 10" dob.    I found the C9.25 to be heavy enough to require an EQ-6 class mount and 30 lbs of counterweights.

 

There are truss Dob OTAs out there that weigh less than the counterweights required for the C 9.25, and that will give far better performance.

 

I move my 12" dob out and set it up quicker and more easily than I could move out my C9.25.

 

Also, A 10" dob will give a bigger true field with a binoviewer too even with a 1.3x OCS.

 

C8 is Compact and easy..  Past that and in my own opinion, you really have to step up the effort necessary to get the scope out the door and this makes just enough difference to make it less likely to get used.

 

I enjoyed reading your experiments though, and your experiences generally match mine.    The C9.25 (and in fact all of the SCTs I have owned except the EdgeHD) are poor off axis performers.  Like you, I found no benefit to the .63 reducer. 

 

The high magnification of Nagler type eyepieces (for a given true field) showed the bloated stars far more than a Panoptic with a similar sized true field did, so I stopped using 82 degree types and went exclusively to Panotics in the SCTs (except the EdgeHD which was nothing sort of marvelous with a 31mm Nagler).

 

The 6" Apo did not give the resolution on Globulars (as you also have seen) but many of the fainter stars were indeed still there if one looked for them.   The pin **** stars of the Apo don't show with the same authority as they do in the 9.25, but careful scrutiny shows that there are more stars there than would be evident at a glance.

 

I did not care for the C9.25 in the end and quickly moved past it to the C11.  It mounts on the same class mount, has much better planetary performance, goes much deeper, and only weighs a few pounds more.

The C9.25 works fine for visual on a CG5-GT class mount.  Piece of cake.  My EM-200 is massive overkill for the C9.25.

 

B2_zps2vj3uel2.jpg

 

- Jim


Edited by jrbarnett, 11 December 2016 - 08:17 PM.


#33 jrbarnett

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Posted 11 December 2016 - 10:22 PM

 

I just came from outside with the Edge 8. It took me 3 minutes to set everything back inside. It's so easy it makes me want to go outside every clear night. It took the Edge about 1h-1h15mins to show pin point stars across the entire fov. It was 15 Fahrenheit and seeing/transparency was average, maybe a little bit better.   

 

... without going the extra expense of the Edge or ACF design (and I personally feel quite an overpriced extra).

 

+1; especially on the C9.25.  EdgeHD makes a much bigger difference on the 8" and 11" with their swoopy, curvy native fields.  The inherently flatter C9.25 standard benefits less from Edge HD treatment than do the others.

 

That said, there are two meaningful advantages for the C9.25 Edge over the standard version; the vents and the larger rear aperture.  Edge HD C9.25s vignette less than do the pinhole rear ported standard C9.25s.  Better illumination of wide field low power eyepieces combined with faster cooling and a flatter field make for prettier views when looking at things that benefit from wider fields of view.  On axis, there's no advantage.

 

Were I to do it over, I'd probably not opt for the Edge version on account of the cost difference, but the performance differences between the two designs are material.  For others I could easily see the price difference being "worth it".

 

The other thing worth noting about the C9.25 is its whopper CO.  This affects contrast and image quality by putting a lot of energy where it does not belong.  But if you also have a big 'frac, you don't care.  You get cheap easily mounted aperture for DSOs in the guise of the C9.25 and great contrast with the big 'frac.

 

I think your strategy of combining 6" f/8 ED doublet and standard C9.25 as companion OTAs is brilliant and entirely rational.

 

Regards,

 

Jim


Edited by jrbarnett, 11 December 2016 - 10:36 PM.


#34 stevecoe

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Posted 12 December 2016 - 03:44 AM

Howdy all;

 

Well, if you also read my post, it is about 15 down from this one, you know I am happy with my 9.25" under Arizona skies.  I guess I don't have the critical eye anymore and I use nothing but Panoptic eyepieces--35, 27 and 22 for wide field views.  I knew the 9.25 would not get the Double Cluster to fit, but I had decades of viewing them with a variety of telescopes meant to provide wide field views--TV 102, 6" Mak-Newt and like that.  It seams to me that trying to get a wide field view with a big SCT is like trying to drag race a Volkswagen.

 

For the objects I wanted to view, my 9.25 does a fine job.  Put in the 27mm Panoptic in the 2 inch diagonal and aim it at any Messier open cluster this winter--M 34, 35, 36, 37, 38, 52 and like that.  You will find a cluster that takes up 50 to 80 percent of the field of view and shows lots of small star points in beautiful chains.  Just what I wanted.

 

Aim it at any bright or pretty bright planetary nebula and run the power up to 250X or more (if the night will take it) and there is plenty of detail and nice greenish color to enjoy.  The Orion Nebula is absolutely fascinating as you combine different magnifications and filters.

 

For me, I have given up on undriven scopes and I love having my SCT on the CGEM.  It is perfect for GOTO visual and wide piggybacking imaging with my DSLR.  I can set it up in half an hour and I need 15 minutes or so in twilight to get it aligned to the Pole.  By the time it is good and dark I am ready to view the night sky.

 

This is my 38th telescope over the 40 years I have lived in Arizona, I have generally owned them 2 at a time, one for general and high power viewing and one for wide field.  Right now I have an Apogee 88mm binocular for wide viewing and I am having a ball.

 

Lots to enjoy;

Steve Coe

 

9pt25 SCT at Fred's Meadow June 2015 (Medium).JPG



#35 doctordub

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Posted 12 December 2016 - 04:57 PM

 

 

I just came from outside with the Edge 8. It took me 3 minutes to set everything back inside. It's so easy it makes me want to go outside every clear night. It took the Edge about 1h-1h15mins to show pin point stars across the entire fov. It was 15 Fahrenheit and seeing/transparency was average, maybe a little bit better.   

 

... without going the extra expense of the Edge or ACF design (and I personally feel quite an overpriced extra).

 

+1; especially on the C9.25.  EdgeHD makes a much bigger difference on the 8" and 11" with their swoopy, curvy native fields.  The inherently flatter C9.25 standard benefits less from Edge HD treatment than do the others.

 

That said, there are two meaningful advantages for the C9.25 Edge over the standard version; the vents and the larger rear aperture.  Edge HD C9.25s vignette less than do the pinhole rear ported standard C9.25s.  Better illumination of wide field low power eyepieces combined with faster cooling and a flatter field make for prettier views when looking at things that benefit from wider fields of view.  On axis, there's no advantage.

 

Were I to do it over, I'd probably not opt for the Edge version on account of the cost difference, but the performance differences between the two designs are material.  For others I could easily see the price difference being "worth it".

 

The other thing worth noting about the C9.25 is its whopper CO.  This affects contrast and image quality by putting a lot of energy where it does not belong.  But if you also have a big 'frac, you don't care.  You get cheap easily mounted aperture for DSOs in the guise of the C9.25 and great contrast with the big 'frac.

 

I think your strategy of combining 6" f/8 ED doublet and standard C9.25 as companion OTAs is brilliant and entirely rational.

 

Regards,

 

Jim

 

My rational exactly! I have the Astro-Physics 2" visual back and 2.7" to 3.25 Celestron adapter so my 41mm Pan and 31mm Nagler will not be vignetted.

CS

Jonathan



#36 starcam

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Posted 13 December 2016 - 01:50 AM

Well I hope Bill buys it, it will help my family be able to give christmas presents As I spent all my money on eyepeices..

I have seen no problems with a 35pan in tha c9.25. I believe it has to do with the rotation -/+ at that that focal that length., because the xw's were for spotting scopes.

The problem is the pentax xw, not the scope.clockwise or clockwise angular rotation of the xw.

Throw in a 31 nag in there, it will be well corrected. I use the 28 uwan, felt like I was in space.


Edited by starcam, 13 December 2016 - 02:13 AM.


#37 Procyon

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Posted 13 December 2016 - 07:09 AM

Well I hope Bill buys it, it will help my family be able to give christmas presents As I spent all my money on eyepeices..


That gave me a nice laugh this morning...

#38 BillP

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Posted 13 December 2016 - 01:18 PM

...my 41mm Pan and 31mm Nagler will not be vignetted.

 

 

My 2" max TFOV EPs do not vignette either in this standard C9.25 worth any mention.  It's only when they are used in conjunction with the .63x reducer that they vignette.




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