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Comparison with Hubble.

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#26 BQ Octantis

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Posted 02 October 2021 - 06:23 AM

Ok, Borodog, thanks to your ponderment I can more clearly see (if you'll pardon the pun) what my 7-in aperture is capturing as compared to the Hubble. For the last couple of years, I've been painfully aware of the trade between detail, artifacts, and noise from my 7-in Mak. But as it turns out, the aperture holds its own pretty well—even against Hubble.

 

For starters, here is my processed image with the best method I have available to date. Full sensor FOV, full sampling pixel scale:

 

(Click for full size.)

gallery_273658_12412_38141.jpg

 

First, I've always gotten some amount of albedo variation in the NPR, but I've never assessed what it correlated with. But since I was just two days from the Hubble, those details don't change that quickly. So if I derotate Hubble and mine so I can accomodate spatial distortions, I can do an almost (~within a few revolutions) apples-to-apples between my scope and Hubble:

 

(Click for animation.)

gallery_273658_12412_37823.png

 

Second, the GRS. In spectacular seeing, I get a lot of little features that I've never known whether they have anything to do with reality. But thanks to your query (and the two days between my best-ever seeing and Hubble), I can piece together what my scope actually captured:

 

(Click for animation.)

gallery_273658_12412_2933.png

 

From this analysis, I assess that my Mak's detail cutoff is somewhere between the line spread cutoff and the edge spread cutoff.

 

Thanks for the lesson, Borodog! smile.gif

 

BQ


Edited by BQ Octantis, 02 October 2021 - 06:47 AM.

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#27 GSBass

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Posted 02 October 2021 - 07:56 AM

It really does demonstrate how far lucky imaging has come, I can’t take images like this with my 7” but it’s obvious when you get up to 11 and 14 you can actually do some good comparisons….. on the bright side my scope excels at lunar and I have gotten a few shots i thought compared well with the lunar reconnaissance orbiter..__ I mean not as good…. Just like hubble is better, but still comparable 


Edited by GSBass, 02 October 2021 - 07:56 AM.


#28 dcaponeii

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Posted 02 October 2021 - 11:41 AM


Probably not much better. Ironically, Borodog picked a reference HST image from two nights after my best stretch of seeing ever. I'd been chasing the NTrZ storms, and I had a stretch of 3 hours of good seeing. So it was also the longest session I've ever captured.

But that perhaps brings up a better comparison. The image detail limit is the edge spread function, which we don't have for both apertures. The next best thing is the point spread, to which we can normalize the images. Here's how they compare:

hst2.jpg

Of course, theirs cost US$1.9B. And yet with a US$2000 setup, I got this:

GIF preview:
post-273658-0-55741300-1598260057.gif
24-bit APNG

get.jpg?insecure

You'd think they'd have gotten a bit more for their money.

BQ


Don’t forgot the extra billions for COSTAR plus four servicing missions!
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#29 Kiwi Paul

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Posted 02 October 2021 - 11:18 PM

A very interesting study BQ. It really does show how small amateur telescopes hold up versus Hubble. Surprisingly well! Well done.
Paul

#30 GSBass

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Posted 03 October 2021 - 09:12 AM

It’s kinda inspiring me to do dramatic close in crops of my better captures and reprocess. I think it might be fun because you could take a more artistic approach with all your tools. Obviously through a 7” the red spot will be a mess at 700+x but if you were just processing that from the original stack you could be much more aggressive than you would normally be and no doubt bring out more detail than you normally would feel comfortable doing….. I know we cringe to see over processed images posted but this would be different I think



#31 GSBass

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Posted 03 October 2021 - 10:20 AM

This is kinda what I meant, I didn’t have the ser from a couple of days ago so couldn’t really try to improve sharpness but i resized and cropped and then tried to bring out every color variation recorded, fun experiment regardless , obviously lots of variations that don’t get brought out in our normal photos simply because of aesthetics 

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#32 GSBass

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Posted 03 October 2021 - 10:39 AM

Btw that close up was made from this, I just resized to 1000dpi and did the super aggressive processing

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#33 Borodog

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Posted 03 October 2021 - 06:32 PM

That's a very cool analysis, BQ.



#34 CharLakeAstro

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Posted 03 October 2021 - 10:08 PM

Once the HST is decommissioned and sent to the bottom of the pacific, the demand for earth based visual band images will go up.

BQ Octantis, Ittaku and Borodog to the rescue!!

 

The HST only had narrow band imaging and the colour images are artificial from just a few tiny narrow bands. The JWST unfortunately will not have ANY visible colour imaging possible. It only has 600nm and above, so deep red upwards. 10 billion dollars and it still can't take a darn decent colour photo (I know they don't care about that, but we do.)


Edited by Benschop, 03 October 2021 - 10:09 PM.

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#35 GSBass

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Posted 04 October 2021 - 07:13 AM

It does seem they should plug in a 462c for us before launch ;)

Once the HST is decommissioned and sent to the bottom of the pacific, the demand for earth based visual band images will go up.

BQ Octantis, Ittaku and Borodog to the rescue!!


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