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Man~, M57 is hard!

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#1 Jinux

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Posted 24 September 2021 - 10:59 PM

M57 is very bright PN and I guess it would be the best if taken as lucky imaging with planetary cam. 

But since I decided to take all Messier in a single setup (C11/F6.3) and I'm too lazy to change setup for M57, I just took it with my day to day setup. C11/F6.3+NBZ filter+2600MC.

Testing what exposure works the best was easy part and settled down to 15s because I have matching dark already. Maybe shorter one works better but it would consume too much disk space AND new dark. 1hour exposure consumes 10GiB disk space already.

Real challenge was processing. I can see some hint of outer halo after stacking, but there is NO way I can bring it out without burning out M57. Dynamic range is way too high even with HDR of StarTools. So I gave up and focus on core but it's still hard. Keep ended up with too high contrast or too dim.

After several trial, here is best compromise so far.

 

Ring_9_23_3h-RGB-session_1_redo3.jpg

 

One good thing about processing it dim was that it's easier to bring out details though. 

 

Ring_9_23_3h-RGB-session_1_redo.jpg


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#2 pathint

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Posted 24 September 2021 - 11:06 PM

I kind of like the inner core of M57, like a clear pond :-) 

 

The outer halo is much much dimmer than the core. I believe the only way to bring it out is to blend in narrow band data in Ha into LRGB. Possibly one needs to process the image using HDR.



#3 pixlimit

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Posted 25 September 2021 - 01:33 AM

The ring is beautiful and shows some structures. I applied "deconvolution" in Pixinsight, a powerful tool...



#4 Mert

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Posted 25 September 2021 - 03:03 AM

I settled at 0,5 second exposures with my RC8 plus ASI224MC but didn't try to get the outer halo

Edited by Mert, 25 September 2021 - 03:04 AM.


#5 RogeZ

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Posted 25 September 2021 - 06:50 AM

The bigger question is how did you lose the center stars?

#6 Jinux

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Posted 25 September 2021 - 11:45 AM

The ring is beautiful and shows some structures. I applied "deconvolution" in Pixinsight, a powerful tool...

I tried deconvolution in StarTools. I tried several parameters but didn't help much in this M57. Usually it really helps galaxies and improves some in nebulae though. 

 

I settled at 0,5 second exposures with my RC8 plus ASI224MC but didn't try to get the outer halo

I'm certain it's much better than 15s. I was too lazy to take out the setup to get matching dark. (I found taking dark 'in setup' isn't good way due to light leak.) ... Now I think more, I may design a 2" light blocking filter sized 3D printer model and insert into the filter slider. 

 

The bigger question is how did you lose the center stars?

That's good question and puzzled me as well. I examined the sub and can't get good definition of center star in there. 

100% crop of sub that has HFR = 4.3 and 0.23" RMS guiding error. So it's not focus error or smeared by tracking. 

 

Screenshot 2021-09-25 094201.jpg

 

while my old M57 @F10, unprocessed other than live stack of 5s has center stars though.

I may have to try other exposures to find out.

Attached Thumbnails

  • M57_f10.jpg

Edited by Jinux, 25 September 2021 - 11:48 AM.

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#7 RogeZ

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Posted 25 September 2021 - 12:00 PM

Your stars have weird shapes, for the type of high resolution work you are doing, check collimation first and work at it.

 

Also, dont take phd2 numbers too seriously, if your stars have bad shapes it could still be tracking.



#8 Ivo Jager

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Posted 27 September 2021 - 09:23 PM

NO way I can bring it out without burning out M57. Dynamic range is way too high even with HDR of StarTools.

Quick tip that may help - if you are trying to tame detail in the HDR module that is "squeezed into" a relatively small area of the image (globular clusters, or detail like this in M57), try reducing the Detail Size Range parameter to something way smaller.

 

This parameter gives you control over how the local dynamic range optimized detail "sits" amongst the detail from other dynamic ranges. Smaller values will essentially instruct it to ignore making it work in a larger scale context and really focus on bringing out the nitty gritty.

 

I'm just about to finish up on a brand new HDR module though for 1.8... :)

 

Hope that helps!




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