Struggling newcomer looking for guidance

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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Re: Struggling newcomer looking for guidance

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ldipenti wrote: Thu Nov 05, 2020 12:41 pm Do you think the pattern noise is getting better? I'll continue imaging in the coming days to add more data and see if that helps.
I think it may look a little better, but that may also be because of a different stretch. To do a comparison you could use the manual Develop ("FilmDev" in 1.7.x) with the exact same parameters (after a Wipe) and see what the noise looks like?
Another thing that I read on forums is that I should be adding a lot more dark frames (I take around 20 per session), and that information may be combined with APP's dark frame scaling feature, that seems to allow creating a master dark at day time with lots of frames and then use it in any integration. So, just in case, I've left the ASIAIR shooting 160 x 5 minutes dark frames :)
Great to hear you have a good few leads. Clear skies!
Ivo Jager
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ldipenti
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Re: Struggling newcomer looking for guidance

Post by ldipenti »

Ivo,

Ok, so I've followed your advise to better compare pattern noise, let me know if the procedure is correct:

1) Load the image, using the 2nd button from the left.
2) AutoDev - Keep
3) Crop a square area with the galaxy in the middle (around the same on both images)
4) Wipe - Uncalibrated preset - Keep
5) Develop - 99.5% stretch

This is the side by side comparison (in the same image so that JPEG compression affects both images the same way)
side-by-side.jpg
side-by-side.jpg (483.86 KiB) Viewed 315 times
So with that, I believe adding more data does not get significantly better results, do you agree? :(
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Re: Struggling newcomer looking for guidance

Post by ldipenti »

Just an update: the above results were obtained with ST 1.7-436, and I've just tried 1.7-439 and for some reason, the Wipe phase using the "Uncalib" preset doesn't get an even field.
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Re: Struggling newcomer looking for guidance

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ldipenti wrote: Thu Nov 05, 2020 6:06 pm Just an update: the above results were obtained with ST 1.7-436, and I've just tried 1.7-439 and for some reason, the Wipe phase using the "Uncalib" preset doesn't get an even field.
Apologies! 1.7.439 had a critical bug that would cause most GPU code to misbehave by (sometimes) not processing tasks fully.
This is now fixed in 1.7.440.

For what it is worth, the 13h image appears less noisy. What zoom factor did you use here (for the image)?
Ivo Jager
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Re: Struggling newcomer looking for guidance

Post by ldipenti »

Hello Ivo,
admin wrote: Thu Nov 05, 2020 11:09 pm For what it is worth, the 13h image appears less noisy. What zoom factor did you use here (for the image)?
Don't remember really, but now I've done the same comparison adding a version of the 13h integration using just 1 scaled master dark (as per APP's definition) created from around 130x300sec dark frames. I really don't see much difference with the previous one, but if it works just as good as the usual dark frames, it'll be good to avoid wasting night time to take them instead of imaging the sky.

For this comparison the zoom factor is 100%
comparison.jpg
comparison.jpg (469.22 KiB) Viewed 302 times
So, to try arriving to some conclusion: I think the maximum dither distance (10 px) value that the ASIAIR Pro allows is not enough to overcome the pattern noise of my Nikon D500, and it seems that I would mitigate this by adding LOTS of additional integration time. For accomplish this easier, I could use the scaled master dark feature from APP, maybe taking some more dark frames during the day time and devoting the entire night time to image.

If you have any other suggestions, they'll be welcome! All in all, it's really interesting that StarTools allows me to detect problems on the imaging and/or stacking phases, giving me the opportunity to correct the problems at the root source instead of blindly trying to counter them in post processing.

Best regards,
Lucas.
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Re: Struggling newcomer looking for guidance

Post by ldipenti »

As a bonus, I attach the edited result of 13h integration with the scaled master dark. I think it looks very good!
Sculptor_13hs_scaled_darks-20201008_20201009_20201011_20201101_20201102_20201103.jpg
Sculptor_13hs_scaled_darks-20201008_20201009_20201011_20201101_20201102_20201103.jpg (388.49 KiB) Viewed 301 times
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Re: Struggling newcomer looking for guidance

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Nice work Lucas!
If you have any other suggestions, they'll be welcome!
If 10 pixels is not enough, you could always nudge the scope manually a few times during acquisition (wait 30s for any vibrations to stabilise in the setup before continuing acquisition).
Ivo Jager
StarTools creator and astronomy enthusiast
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