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Classic C8 vs Edge With Reducers

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#1 skyler

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Posted 21 July 2018 - 08:00 PM

I am a former proud owner of a '77 orange tube C8. Have also owned newer non-Edge Celestron OTA versions inclusive up to C11.  I see classic C8s available for bargain used prices and just at a stage of window shopping at this point.  I know there are a few Celestron users out there and wondered for imaging with a full frame camera like a 6D or A7s what would be a recommendation between a new C8 Edge with a focal reducer or a classic C8 using a reducer/corrector? I'm more focused on flatness of field and quality of the image but can sacrifice a little difference in the sharpness/IQ of image based on price differential (say a difference of $500 or more).

 

Barring the central obstructions issues, cooling, mirror shift or of the inherent issues of the classic vs the modern design, would they yield mostly equal results for AP imaging fitted in the manner as described?  Would one be considered better at producing a better image and, again, is it worth the price differential between a new Edge with reducer versus the much simpler less expensive classic with the reducer/corrector.

 

If there is a post or thread somewhere that I have not found, please feel free to direct me there.

 

 

Thank you !

 

Skylar



#2 Eddgie

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Posted 21 July 2018 - 09:08 PM

No one but you can answer if it is worth it, but the off-axis performance of the EdgeHD is vastly better than in the C8.  Even visually the difference is very easy to see when using modern wide field eyepieces like the 31mm Nagler.  The field is about three times flatter and there is no coma.  It is a huge improvement.

 

Is it worth it though? I would say only if that matters to you and may depend on the size of your chip, but the EdgeHD is in my own opinion a superior instrument for imaging. I just can't tell you if it is worth the price difference or not. 



#3 skyler

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Posted 21 July 2018 - 10:08 PM

Thanks for the feedback Eddgie. Just for clarification, you are suggesting that it is vastly better given the conditions mentioned?  C8 Edge with reducer vs C8 with Celestron reducer/corrector ?

 

I expect some edge loss with the full frame DSLR vs a APS-C astro cam and would mostly be using the full frame with this scope.


Edited by skyler, 21 July 2018 - 10:18 PM.


#4 Luna-tic

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Posted 22 July 2018 - 12:03 AM

If you read the Edge HD white paper, they (Celestron) discuss the optical and performance differences between the standard C series and the Edge. Their  goal with the Edge was to correct the shortcomings of the standard Schmidt-Cassegrain design and optimize the platform for imaging. I own a C6 and an Edge 8; the difference in aperture notwithstanding, there is a huge difference in their performance. Not to say the C6 isn't a good scope; it is and I enjoy using it, but the Edge is significantly better. The reducer/corrector does improve the Standard C scope, but the Edge still surpasses it, especially when used with its own reducer.

https://s3.amazonaws...paper_final.pdf


Edited by Luna-tic, 22 July 2018 - 12:05 AM.


#5 rmollise

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Posted 22 July 2018 - 09:06 AM

I am a former proud owner of a '77 orange tube C8. Have also owned newer non-Edge Celestron OTA versions inclusive up to C11.  I see classic C8s available for bargain used prices and just at a stage of window shopping at this point.  I know there are a few Celestron users out there and wondered for imaging with a full frame camera like a 6D or A7s what would be a recommendation between a new C8 Edge with a focal reducer or a classic C8 using a reducer/corrector? I'm more focused on flatness of field and quality of the image but can sacrifice a little difference in the sharpness/IQ of image based on price differential (say a difference of $500 or more).

 

Barring the central obstructions issues, cooling, mirror shift or of the inherent issues of the classic vs the modern design, would they yield mostly equal results for AP imaging fitted in the manner as described?  Would one be considered better at producing a better image and, again, is it worth the price differential between a new Edge with reducer versus the much simpler less expensive classic with the reducer/corrector.

 

If there is a post or thread somewhere that I have not found, please feel free to direct me there.

 

 

Thank you !

 

Skylar

 

It depends on you. Yes, the field of the Edge is noticeably  better than that of a standard C8 (orange or otherwise) equipped with a reducer. However, is it worth a considerable amount of extra money? Only you can decide that. ;)


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#6 skyler

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Posted 22 July 2018 - 12:17 PM

Luna-tic, Thanks for the reminder to the white paper. It has been some time since I read that and it was good to reread it again.

 

Uncle Rod, Glad to hear your perspective on this as you have been on the Schmidt-Cass scene for so many years. Yes, so right about ones real needs. If it is noticeably better with the conditions stated, then I assume that to be at least visually so that can translate to very noticeable in imaging results (an assumption). So now it would just be the difference in $ and personal expectations.

 

One last question is do you think or heard rumblings that these EdgeHD scopes will be made in an F8 design or is this an issue with the complexities noted in the white paper and of course the obvious is with central obstruction issues?  


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#7 Jon Isaacs

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Posted 22 July 2018 - 12:31 PM

It depends on you. Yes, the field of the Edge is noticeably  better than that of a standard C8 (orange or otherwise) equipped with a reducer. However, is it worth a considerable amount of extra money? Only you can decide that. wink.gif

 

How does the Starzona corrector/reducer fit in?

 

https://starizona.co...-coma-corrector

 

Jon



#8 Luna-tic

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Posted 22 July 2018 - 12:55 PM

How does the Starzona corrector/reducer fit in?

 

https://starizona.co...-coma-corrector

 

Jon

Very expensively grin.gif .  What makes that one better than the 0.63 reducer/corrector that Celestron designed specifically for the C-series, and costs half as much? I have the .63 Celestron part and it does markedly improve the C6 performance, both visually and photographically.

 

As to Skyler's comment about hints or rumors of a f/8 version of the SCT, why bother, when with the standard C6 you have a choice of native f/10, or reduced/corrected at f/6.3? And with the Edge, you can go native f/10, reduced f/7, and f/1.9 (8") with Hyperstar.

 

I know sometimes budget does speak loudest when deciding on something expensive like these are, but I took the 'buy once, cry once' approach, knowing I'd probably regret limiting my options if I took the other approach.



#9 skyler

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Posted 22 July 2018 - 01:07 PM

Thanks for adding this to the mix Jon.  Yes, points def. noted Luna-tic yet I am still open to options and if I can image in the F6 range and how effectively/practically I can get there.  I would not rule out a used Edge but I do have an irrational fondness for a nice performing classic C8 since it was my first big scope I saved up for as a tween-ager.

 

I will say with near certainty, though, that I won't be getting into Hyperstar at this time.  IF I did, in the future, it would be with a larger aperture Celestron.



#10 Eddgie

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Posted 22 July 2018 - 01:44 PM

Thanks for the feedback Eddgie. Just for clarification, you are suggesting that it is vastly better given the conditions mentioned?  C8 Edge with reducer vs C8 with Celestron reducer/corrector ?

 

I expect some edge loss with the full frame DSLR vs a APS-C astro cam and would mostly be using the full frame with this scope.

Yes.  The reducer on the standard C8 could slip buy in the days of film based imaging, but modern high resolution camera chips will show the difference.

 

If not, then there really would not be a market for the EdgeHD.  Right?  It has to be better to justify the price, and yes, it is better.

 

Once again, impossible for me to say that it is worth it but I can tell you that objectively, the EdgeHD offers a substantial improvement in across the field performance vs the older design. Just can't say it is enough for you to say it is worth the money.



#11 REC

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Posted 22 July 2018 - 02:04 PM

Very expensively grin.gif .  What makes that one better than the 0.63 reducer/corrector that Celestron designed specifically for the C-series, and costs half as much? I have the .63 Celestron part and it does markedly improve the C6 performance, both visually and photographically.

 

As to Skyler's comment about hints or rumors of a f/8 version of the SCT, why bother, when with the standard C6 you have a choice of native f/10, or reduced/corrected at f/6.3? And with the Edge, you can go native f/10, reduced f/7, and f/1.9 (8") with Hyperstar.

 

I know sometimes budget does speak loudest when deciding on something expensive like these are, but I took the 'buy once, cry once' approach, knowing I'd probably regret limiting my options if I took the other approach.

If you are interested in a f/8 version of a SCT, Meade now offers one in their LX 600/850 series, with ACF optics. Expensive though.


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#12 skyler

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Posted 22 July 2018 - 02:17 PM

Thank you REC.  Yes, I did see their offerings and it is certainly a consideration. Again it would be a used market option and it adds a hitch to the equation.  How do you like yours, have you used it for DSO imaging and would you do it over again? I know yours is probably not the F8 version but still would be open to hear your opinion.

 

Now that I think of it, it was the 10" Meade OTA that was F8 and not the 8" of what i was looking at. The newer version you mentioned I did not recall if the 8" came as an OTA only.


Edited by skyler, 22 July 2018 - 02:46 PM.


#13 Luna-tic

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Posted 22 July 2018 - 03:51 PM



I expect some edge loss with the full frame DSLR vs a APS-C astro cam and would mostly be using the full frame with this scope.

"Our most important design goal was to eliminate coma and field curvature over a field of view large enough to accommodate a top-of-the-line, full-frame, digital SLR camera or larger astronomical CCD camera. This meant setting the FOV at 42mm in diameter. Of course, any design that would satisfy the full-frame requirement would also work with the less expensive APS-C DSLR cameras and less expensive astronomical CCD cameras." White Page

 



If you are interested in a f/8 version of a SCT, Meade now offers one in their LX 600/850 series, with ACF optics. Expensive though.

I already have one I can use at f/7.



#14 rmollise

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Posted 22 July 2018 - 04:24 PM

Yes.  The reducer on the standard C8 could slip buy in the days of film based imaging, but modern high resolution camera chips will show the difference.

 

If not, then there really would not be a market for the EdgeHD.  Right?  It has to be better to justify the price, and yes, it is better.

 

Once again, impossible for me to say that it is worth it but I can tell you that objectively, the EdgeHD offers a substantial improvement in across the field performance vs the older design. Just can't say it is enough for you to say it is worth the money.

Not really. Fine grain 35mm film like Tech Pan was VERY high resolution. The r/c did a fine job with it and will do a fine job with a CCD.



#15 Jon Isaacs

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Posted 22 July 2018 - 07:10 PM

Very expensively  What makes that one better than the 0.63 reducer/corrector that Celestron designed specifically for the C-series, and costs half as much?

 

 

4 elements versus two elements??? 

 

$400 is a lot less expensive than the edge plus reducer..

 

Jon



#16 skyler

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Posted 22 July 2018 - 10:37 PM

I am beginning to see the relative costs of imaging close to F6 between the two designs and what I am willing to compromise at the same time.



#17 skyler

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Posted 23 July 2018 - 02:24 PM

I asked Dean at Starizona about their new reducer/corrector and he replied with some basic feedback:

 

"Celestron’s reducer corrector does reduce but does not correct.  Stars will be comatic on the outer edges of the image field with Celestron’s unit.  Our version both reduces and corrects.  You basically get HD performance with a standard SCT optical tube."

 

I casually compared their website spot diagram (assumptions made regarding the graph) to the white paper EdgeHD info on the Celestron site and it does compare favorably to the 10 and 15mm off axis distances. Of course not sure which scope is being highlighted but at this very first glance, on the surface, it looks quite good for my purposes.   I am hoping to see more examples of images. and further opinions from actual users regarding performance. Oh, and I did see the examples on the Starizona site plus an Astrobin user from CN posting there as well.

 

I think I found some info/examples onsite here on CN so I will do some reading.


Edited by skyler, 23 July 2018 - 05:18 PM.

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#18 skyler

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Posted 09 December 2018 - 01:03 PM

Having chosen a totally different Vixen option I was very pleased with the results but now I have the option to add a C8 Edge but want to include their .7x reducer for imaging.  I read the usual Celestron info for the 8" Edge .7x reducer and it notes that it is optimized for APS-C cameras. The C9.25 and C11 Edge reducers do not make this statement in their advertisements.  I've seen photos on Astrobin in this C8 Edge with .7x reducer configuration but I am not sure if the imager is cropping these and just what are the limitations with full frame imaging results.

 

Can anyone speak about this from experience or even send me a link to more info regarding this question?

 

 

Thanks !

Skylar


Edited by skyler, 09 December 2018 - 01:07 PM.


#19 skyler

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Posted 09 December 2018 - 02:18 PM

I think I have some feedback on this from a vendor that this truly is optimized for the APS-C frame and there may well be a 15% unusable area on the image circle using the .7x reducer for 35mm sensors.  Any other feedback is still welcome.


Edited by skyler, 09 December 2018 - 03:06 PM.


#20 Achernar

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Posted 13 December 2018 - 06:24 PM

One factor to consider is only the reducers made specifically for the EdgeHD's work with those telescopes. Reducers made for the classical SCT's will not work properly on the EdgeHD's and vice versa. You can however use a Meade F/6.3 focal reducer on a Celestron and vice versa with either company's SCT's. You can also use the Meade F/3.3 reducers for imaging only with either brand of classical SCT if memory serves.

 

Personally, I have an 8-inch EdgeHD SCT and the .7X reducer for it, and I am glad I spent the extra money for both. I feel the improved views visually alone are worth it since I use ultra-wide angle eyepieces all the time.

 

Taras



#21 Traveler

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Posted 14 December 2018 - 12:25 AM

Did someone tried those 1.25 inch, 0.5 x reducers like the one from Atik or this one (1.25) or this (2 inch) from TS? If so what are your visual/photopgraphic experiences with such?


Edited by Traveler, 14 December 2018 - 01:12 AM.



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