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Dust that moves

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#1 limeyx

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Posted 14 April 2021 - 05:36 PM

So I usually take flats inside the next day but I can see I may have to revise that and do them outside.

 

I have the case where my flats now have a dust spot that my lights do not and its causing a blob in the integrated image

 

Pondering the best way to fix. Options seem to be

 

 

- Crop smaller (might work in this case due to galaxy season and wide FOV)

- Clone stamp on the master flat and re-integrate. Seems OK but I might get a small undercorrection of vignette in that area

- Clone stamp each of the flats and re-create master flat

- Use yesterdays flats (They dont have the spot)

- Clone stamp the final integrated image

 

Wondering what people have used that seems to work the best here ?

 



#2 Mike in Rancho

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Posted 14 April 2021 - 06:16 PM

Ouch!  At least it wasn't the lights.  On my Chain I was watching the subs come in to BYN and suddenly noticed these moving dust spots and squiggles.  I hit suspend and actually took the camera off the scope (while it kept tracking and guiding) to do a blow-out and a wet sensor clean.  Man the stuff that falls down into the camera when the scope points straight up...

 

Luckily it was just a few subs with spots, and I could make them disappear by lowering the kappa.  If the spot isn't in all your subs, and with these being only flats, if you squeezed the kappa rejection down to 2.0 or something, they might go away.

 

Other than that, if only vignetting is a concern, I'd either take new flats or reuse a prior "no dust" session.

 

Other times I've done healing at the end of processing on any resultant black holes left by dust motes.  I presume PI has some kind of intelligent heal function that'll be much better than clone stamping?


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#3 limeyx

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Posted 14 April 2021 - 06:56 PM

Yeah moving dust is the worst. I got this DSLR used and I feel like its a dust-collector.

 

I'm re-stacking with yesterdays flats to see how that goes.



#4 Stelios

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Posted 14 April 2021 - 07:00 PM

It's very simple to fix a dust donut with Pixinsight--use the GAME script, create an ellipsoid mask covering the donut exactly, and use curves as needed to match the illumination. 

 

Of your options--use yesterday's flats.


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#5 calypsob

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Posted 14 April 2021 - 11:53 PM

It's very simple to fix a dust donut with Pixinsight--use the GAME script, create an ellipsoid mask covering the donut exactly, and use curves as needed to match the illumination. 

 

Of your options--use yesterday's flats.

Do you do this on the master calibrated and stacked light frame?  I have a really annoying set of dust bunnies in a long integration. 



#6 limeyx

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Posted 15 April 2021 - 12:02 AM

It's very simple to fix a dust donut with Pixinsight--use the GAME script, create an ellipsoid mask covering the donut exactly, and use curves as needed to match the illumination. 

 

Of your options--use yesterday's flats.

Yup. I need to start working with the GAME script. Re-processed it and the calibrated lights look a lot better at least. Tonight I do flats outside



#7 Stelios

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Posted 15 April 2021 - 01:15 AM

Do you do this on the master calibrated and stacked light frame?  I have a really annoying set of dust bunnies in a long integration. 

Yes. The GAME script is really a game-changer (and I hate that expression). It has enormous flexibility and applicability.


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#8 Marcelofig

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Posted 15 April 2021 - 02:52 AM

Adam Block has a new technique for dealing with things like moving dust directly during calibration.

 

https://www.youtube....h?v=ZZVJKo47Ctk


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#9 limeyx

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Posted 15 April 2021 - 10:05 AM

Well hopefully this is solved for the future mostly. I've been taking flats the day after, partly because I was taking them at 2, 2.5 and 3 seconds (due to prior flats woes)

 

2.5 seconds really works so I cut down to just that. This shortened the time considerably.

 

I also use a trace-pad with paper on it, and it's been really damp out until this week when I am done, so I did not want to get my paper soggy (I need to move to translucent plastic but I am not wanting to mess with a "good thing" since it took forever to get where I am good)

 

Last night, I just turned off the tracker, pointed it directly up & locked it down and took flats (&flat darks which I probably don't even need) and then was done. Super easy (and the new dust spot is still there which is good)
 



#10 limeyx

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Posted 15 April 2021 - 10:06 AM

Adam Block has a new technique for dealing with things like moving dust directly during calibration.

 

https://www.youtube....h?v=ZZVJKo47Ctk

Yeah. This was in *every* flat frame so I (think) I would end up with a hole in my master flat here



#11 michael8554

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Posted 15 April 2021 - 10:24 AM

Have you turned off the sensor cleaning function that comes on when you switch off the camera?

 

That will shake the dust around !



#12 limeyx

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Posted 15 April 2021 - 10:31 AM

Have you turned off the sensor cleaning function that comes on when you switch off the camera?

 

That will shake the dust around !

Good point. Yes ... AND it just went in to get modded so it's possible that got changed. My understanding is that modding breaks sensor cleaning though so there *should* be no way it could be on, but it is worth checking

 

Thanks



#13 limeyx

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Posted 15 April 2021 - 01:14 PM

Previous days flats did not work perfectly. Still a bit of a smudge.

 

I may be able to crop around it, or may go back and try to fix it a different way. Maybe I will stack everything first since its not in all the frames

 

So far I have

 

107x180s

201x60s (the bad ones)

80x120s

 

Probably get another 80-100 120s ones tonight if I can keep my eyes open



#14 gdavis

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Posted 16 April 2021 - 12:25 AM

I did my first set of images for stacking with a DSLR a couple weeks ago and noticed dust moving through pretty much all the frames.  At one point I could actually watch a speck walk across the frame as I stepped through about 6 images crazyeyes.gif  Though I was going crazy, glad it's not just me.



#15 limeyx

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Posted 16 April 2021 - 09:25 PM

I did my first set of images for stacking with a DSLR a couple weeks ago and noticed dust moving through pretty much all the frames.  At one point I could actually watch a speck walk across the frame as I stepped through about 6 images crazyeyes.gif  Though I was going crazy, glad it's not just me.

Yup been there -- super super frustrating when you blink the frames and see the dust animate itself




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