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Can a C11 keep up with a 10 inch apo on planets for imaging?

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#1 Darren Drake

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Posted 25 January 2023 - 07:57 AM

I've recently had an online discussion regarding this very question.  It started when a friend shared a Mars image taken with a high end 10 inch TMB apo when Mars was 20.2 arcseconds.  I then shared a recent Mars image taken with my C11 when Mars was 15.4 arcseconds.  Neither if us are experienced planetary imagers but I believe we used about the same level of stacking and enhancing.  To me the images are about of equal quality and any differences in the scope's capabilities are trivial.  

I know in a head to head comparison for visual the 50k apo will definitely give the better image with better more pleasing contrast.  However with its slight aperture edge the C11 will keep up for resolution and be able to keep up for the most part but still definitely loose out.  

In an imaging comparison I believe a C11 can basically keep up with a 10 inch apo if similar levels of enhancing are applied.   The first pic is Mars with the 10 inch TMB at 20.2 arcseconds and the second is my image on 12/26/22 with my C11 at 15.4 arcseconds.   Thoughts on such a comparison??

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Edited by Darren Drake, 25 January 2023 - 08:06 AM.

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#2 gstrumol

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Posted 25 January 2023 - 08:19 AM

I agree (and imagine what the C14 could do!). The SCT is often maligned as a "jack of all trades, master of none" but when it comes to planetary/lunar imaging the best practitioners in the world use them. Not APOs, not Dobs, not Maks - SCTs. Actions speak louder than words, right? wink.gif

 

I think the question should be reversed!

 

Gary


Edited by gstrumol, 25 January 2023 - 08:21 AM.

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#3 John Miele

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Posted 25 January 2023 - 08:57 AM

For planetary imaging, I would think they are pretty even steven. The C11 has 10% more resolution but the 10" APO has no central obstruction, hence a little better contrast. But for planetary imaging, the contrast enhancements provided by the software make the APO contrast advantage less important. Then again, the C11 MUST be perfectly collimated and thermally stabilized to reach peak performance. So, I think it's a wash (and your examples support this) and the local seeing where the two scopes are located will make the real world difference in the finale images.

 

But a quality 10" APO is also a 'freakin unicorn scope! Most any modestly well to do astronomer could afford a C11. But a 10" APO is like unobtanium to 99% of us! 

 

cs...John


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#4 bbasiaga

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Posted 25 January 2023 - 10:30 AM

10" APO----what kind of mount do you need for that?  Got a picture?  

 

Zoinks.  

 

Since planetary imaging is so much about focal length and atmospheric conditions, my non expert eye would say its not possible to truly call the contest.  No way of knowing if those were taken in the same conditions, side by side etc.  But I would say they look close enough to say there is at least a competition.

 

For sure one could say most people's planetary images with a 10" APO just wouldn't exist.  Therefore those taken by an 11" SCT would be better!

 

 

-Brian


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#5 MKV

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Posted 25 January 2023 - 10:58 AM

I know in a head to head comparison for visual the 50k apo will definitely give the better image with better more pleasing contrast.  However with its slight aperture edge the C11 will keep up for resolution and be able to keep up for the most part but still definitely loose out.

First, in both cases the images will be "swimming" and going an out of focus like crazy due to atmospheric conditions, unless both scopes are somewhere way up in the Alps (like Pic du Midi in the Pyrenees, Mattehorn in the Alps, in the Chilean Andes, or Mauakena in Hawaii, etc.).

 

Both telescopes would have to be very close to each other, equally thermally stable, and their images displayed on a split monitor screen simultaneously. There is no point in stacking and "pushing" as it used to be called film emulsion processing, since you're talking direct observing. That also brings individual observer's visual acuity  due to age and visual correction as a modifying factor. 

 

Depending on the "seeing," scintillation frequency could cause the image to go in an out of focus too quickly for the eye to notice any difference, or to be able to distinguish atmospheric artifacts vs real differences in telescopes' perofrmace, live.

 

So, while intriguing and interesting, it's all speculative, highly unlikely to happen, never mind scientific value, if any. 


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#6 starcanoe

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Posted 25 January 2023 - 11:53 AM

Bit of an aside....keep in mind visual VS imaging.

 

That large obstruction on a C11 does a fair bit of "optical" damage. Digital image processing can remove that damage a fair bit. The human eye however can not remove it.

 

I suspect something like an 8 inch apo give or take would be better visually than a C11.

 

And if you were using FILM I'd suspect the 10 inch apo image would be significantly better.

 

Another consideration is that a batch of random SCT scopes are probably have a lot more optical quality variation than a large apo.

 

Just my two bars of gold pressed latinum...


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#7 cuzimthedad

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Posted 25 January 2023 - 02:03 PM

Moving to Major and Minor Planetary Imaging...



#8 RedLionNJ

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Posted 25 January 2023 - 03:19 PM

The images, as presented, are a totally invalid basis for comparison. And the pie chart below isn't even starting to consider post-capture tools/skills:

 

pie_chart.jpg

 

You would need to execute both captures with identical capture settings, essentially side-by-side at the same few minutes.  Then you'd also have to process each one optimally for the optics/conditions.

 

Then, maybe we could do a valid comparison.

 

 

 

 


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#9 Tulloch

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Posted 25 January 2023 - 04:09 PM

I agree with Grant on this, the provided images are really not definite proof either way.

 

For example, here's my best Mars image (taken a couple of years ago with a 9.25" SCT), which I believe is better than the image taken with the 10" APO. Seeing was very good that night and Mars was around 18.7 arcsec in size. Other people have taken better images of Mars with a 9.25" SCT (KiwiRay for instance), the quality of the images are very dependent upon seeing conditions at the time.

 

4. Mars, 2020-11-08

 

Andrew


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#10 Kokatha man

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Posted 25 January 2023 - 06:43 PM

...just a cheeky alteration to Grant's Pie Chart...I've tinted the "focus" & "collimation" segment colours with that of the "experience" to let people know that the latter can have quite a profound effect upon those other 2 aspects! wink.gif

 

But in essence the responses hit the nail on the head in these sorts of discussions.

 

GrantsPie.png

 

 



#11 MitchAlsup

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Posted 25 January 2023 - 08:20 PM

I've recently had an online discussion regarding this very question.  It started when a friend shared a Mars image taken with a high end 10 inch TMB apo when Mars was 20.2 arcseconds.  I then shared a recent Mars image taken with my C11 when Mars was 15.4 arcseconds.  Neither if us are experienced planetary imagers but I believe we used about the same level of stacking and enhancing.  To me the images are about of equal quality and any differences in the scope's capabilities are trivial.  

I know in a head to head comparison for visual the 50k apo will definitely give the better image with better more pleasing contrast.  However with its slight aperture edge the C11 will keep up for resolution and be able to keep up for the most part but still definitely loose out.  

In an imaging comparison I believe a C11 can basically keep up with a 10 inch apo if similar levels of enhancing are applied.   The first pic is Mars with the 10 inch TMB at 20.2 arcseconds and the second is my image on 12/26/22 with my C11 at 15.4 arcseconds.   Thoughts on such a comparison??

To my eyes, the 10" APO is distinctly better in fine contrast detail.

Exactly what one would expect with no CO against a scope with a 30% CO of similar aperture.



#12 KiwiRay

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Posted 25 January 2023 - 09:22 PM

I agree with those who have pointed our how meaningless it is to compare those two images. Two images captured at different times under different conditions tell us nothing about the relative merits of the telescopes that were used.


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#13 Borodog

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Posted 25 January 2023 - 09:42 PM

Both nice images. You can’t compare them objectively though.
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#14 Ittaku

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Posted Yesterday, 02:34 AM

So many non-committal responses.

 

The answer to the question is yes.


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