Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Where have I gone wrong?

beginner
  • Please log in to reply
15 replies to this topic

#1 maverixsian

maverixsian

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 22 Jan 2020

Posted 31 May 2020 - 09:32 AM

So, 

 

My first time imaging with ASI294 and processing in Pixinsight - have been practicing on some of my DSLR shots in Pixinsight to get the hang of it and all working reasonably ok.

 

Stacked using flats, bias and lights both manually and using batchpreprocessing. Use Auto Background Extraction (also tried Dynamic background extraction) and am left with a lot of red all around which I can't seem to get rid of. 

 

What have I done wrong and is there a way to fix it? Is it because I did not shoot any darks (I believe that I can do this now as my camera is cooled so can just set to cooled to shoot them?) 

 

Have tried as much as I can but am really stumped and as am a beginner worrying that maybe something was wrong when I took the photos - I used unity gain (120), cooled camera and my flats don't show much gradient apart from vignetting, neither do any of the single lights so am stumped! 

 

Thank you so much in advance to anyone who helps me, have learned so much already from people here despite this being my first post 

 

smile.gif

 

 

Attached Thumbnails

  • Screen Shot 2020-05-31 at 15.22.39 2.jpg


#2 Tapio

Tapio

    Mercury-Atlas

  • -----
  • Posts: 2,817
  • Joined: 24 Sep 2006
  • Loc: Tampere, Finland

Posted 31 May 2020 - 09:43 AM

You really should add dark frames to your process - as now lacking darks show as amp glow on the rights.

But that red thing is something else - maybe the result of poor ABE useage.

I'm sure PI experts will tell how to get rid of it.



#3 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 20,201
  • Joined: 27 Oct 2014

Posted 31 May 2020 - 10:46 AM

So, 

 

My first time imaging with ASI294 and processing in Pixinsight - have been practicing on some of my DSLR shots in Pixinsight to get the hang of it and all working reasonably ok.

 

Stacked using flats, bias and lights both manually and using batchpreprocessing. Use Auto Background Extraction (also tried Dynamic background extraction) and am left with a lot of red all around which I can't seem to get rid of. 

 

What have I done wrong and is there a way to fix it? Is it because I did not shoot any darks (I believe that I can do this now as my camera is cooled so can just set to cooled to shoot them?) 

 

Have tried as much as I can but am really stumped and as am a beginner worrying that maybe something was wrong when I took the photos - I used unity gain (120), cooled camera and my flats don't show much gradient apart from vignetting, neither do any of the single lights so am stumped! 

 

Thank you so much in advance to anyone who helps me, have learned so much already from people here despite this being my first post 

 

smile.gif

That's a very nice start.  I can't really say you're oing anything obvios wrong, so I'll say how you can do things right.  <smile>

 

This business is a constant struggle to extract a tiny signal from a sea of all kinds of noise.  You need to use all available tools.  Perhaps the most important one is total imaging time, more is always better.  Another is darks. 

 

Really, it doesn't look like you're making an obvious mistake.  Perhaps just trying to stretch too hard.

 

But, if you want the best feedback, we could use a _lot_ more information.  Details of your equipment, mount, scope, camera.  Some idea of your light pollution level.  Basic is urban, suburban rural.  Next is the Bortle level.  Below is a useful website.  Cooling.  How many subexposures of what length.  How many calibration frames, acquired how.  All software used.  There is no such thing as "too much" information, if you want good feedback about what you could be doing better.

 

How to measure your light pollution level, with a DSLR and a lens, handheld.   "good enough" accuracy for just about anything.

 

https://www.pbase.com/image/37608572

 

Have patience.  It's taken me five years to drag myself to a bit above average.  <smile>  Do the research, this is a knowledge driven activity.  It's crazy complicated, there's far more to learn than you can get from short posts here.  You should have the first book below already.  If not, get it.  You're about ready for the second.

 

https://www.amazon.c.../dp/0999470906/

 

https://www.amazon.c...h/dp/1138055360


Edited by bobzeq25, 31 May 2020 - 10:52 AM.


#4 44maurer

44maurer

    Viking 1

  • *****
  • Posts: 878
  • Joined: 12 Jun 2016
  • Loc: Los Angeles, CA

Posted 31 May 2020 - 10:49 AM

Did you debayer correctly (or is this a function of the batchpreprocessing)?  But odd that stars and galaxies are white.



#5 maverixsian

maverixsian

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 22 Jan 2020

Posted 31 May 2020 - 10:58 AM

Ok, thanks for that, that's just the autostretch but comes up with even a little bit of stretch. 

 

Equipment: 

 

Skywatcher EQM35 Mount

Skywatcher Evostar ED80

ASI294 Colour cooled to -20 and shot with gain 120.

 

100 180 second light frames

100 bias frames shot using asiairpro, made into a superbiad on pixinsight. 

100 Flat frames using white t-shirt with an ipad. 

 

My light pollution level is high -  Bortle 6/7, maybe less at the moment however as a lot of our light comes from the airport which is currently not flying much at all. 

 

First of all I followed Light Vortex Astronomy to the letter: https://www.lightvor....html#Section1 

 

I then tried it using BatchPreProcessing.

 

Both the same. 

Pretty sure I got the debayering correct- it is standard in BatchPreProcess and my camera is RGGB from what I have read. 


Edited by maverixsian, 31 May 2020 - 10:58 AM.


#6 imtl

imtl

    Viking 1

  • *****
  • Posts: 544
  • Joined: 07 Jun 2016

Posted 31 May 2020 - 12:00 PM

Can you upload your master light? No processing at all?



#7 maverixsian

maverixsian

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 22 Jan 2020

Posted 31 May 2020 - 01:01 PM

Can you upload your master light? No processing at all?

https://drive.google...ew?usp=sharing 

 

I think I have attached it here



#8 Alex McConahay

Alex McConahay

    Cosmos

  • *****
  • Posts: 9,123
  • Joined: 11 Aug 2008
  • Loc: Moreno Valley, CA

Posted 31 May 2020 - 01:27 PM

You know, I want to open the discussion about ABE and DBE as possible causes of this kind of problem. This is a good illustration of a phenomenon I have seen lately. Around the bright objects are dark areas. then as one moves away, the background lightens up again. It is like the bright areas are donut holes and the dark surrounding areas the dough of the donut in an otherwise rather bright sky. I'm thinking it has something to do with how the Background extraction methods improperly interpret what is what. 

 

Alex



#9 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 20,201
  • Joined: 27 Oct 2014

Posted 31 May 2020 - 01:43 PM

Ok, thanks for that, that's just the autostretch but comes up with even a little bit of stretch. 

 

Equipment: 

 

Skywatcher EQM35 Mount

Skywatcher Evostar ED80

ASI294 Colour cooled to -20 and shot with gain 120.

 

100 180 second light frames

100 bias frames shot using asiairpro, made into a superbiad on pixinsight. 

100 Flat frames using white t-shirt with an ipad. 

 

My light pollution level is high -  Bortle 6/7, maybe less at the moment however as a lot of our light comes from the airport which is currently not flying much at all. 

 

First of all I followed Light Vortex Astronomy to the letter: https://www.lightvor....html#Section1 

 

I then tried it using BatchPreProcessing.

 

Both the same. 

Pretty sure I got the debayering correct- it is standard in BatchPreProcess and my camera is RGGB from what I have read. 

I presume by "autostretch" you mean using the STF and transferring it to HistogramTransformation?

 

That's a harsh stretch that I pretty much no longer use.  Try arcsinh stretch.  Pretty easy to learn (only two adjustments are needed), you have much more control.  It can help to do it in two stages. 

 

MaskedStretch is another good way to stretch, followed by a manual adjustment of HistogramTransformation (since MaskedStretch can be _too_ gentle).  The default options in MaskedStretch are pretty good, you do need to define a preview for the background reference.

 

You won't go as "deep", but you may lose the red artifact.  Your star color will be better, particularly with arcssinh stretch.  M82 may well show more detail. 

 

Another possibility is to upload your stack (not all the frames) to something like Dropbox, post the link, and let people here take a go at it.  First, you get to see the possibilities.  Second, by us doing that, you may get more feedback about the red artifact.


Edited by bobzeq25, 31 May 2020 - 01:51 PM.


#10 maverixsian

maverixsian

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 22 Jan 2020

Posted 31 May 2020 - 01:47 PM

I presume by "autostretch" you mean using the STF and transferring it to HistogramTransformation?

 

That's a harsh stretch that I pretty much no longer use.  Try arcsinh stretch.  Pretty easy to learn (only two adjustments are needed), you have much more control.  It can help to do it in two stages. 

 

MaskedStretch is another good way to stretch, followed by a manual adjustment of HistogramTransformation (since MaskedStretch can be _too_ gentle).  The default options in MaskedStretch are pretty good, you do need to define a preview for the background reference.

 

You won't go as "deep", but you may lose the red artifact.  Your star color will be better, particularly with arcssinh stretch.

 

Yes - this was just viewing with the STF.  

 

I managed to get the red out through numerous things (that I no longer remember!) but I will definitely try those stretch methods, thank you. 

 

It was more just wondering / not knowing why it was happening so I didn't know what I was doing wrong! 

 

Thank you so much for your advice 



#11 WadeH237

WadeH237

    Fly Me to the Moon

  • *****
  • Posts: 5,772
  • Joined: 24 Feb 2007
  • Loc: Snohomish, WA

Posted 31 May 2020 - 09:50 PM

The image in the first post reminds me of this old thread...



#12 Kevin Ross

Kevin Ross

    Viking 1

  • *****
  • Posts: 934
  • Joined: 28 Mar 2018
  • Loc: Traverse City, MI

Posted 31 May 2020 - 11:10 PM

The image in the first post reminds me of this old thread...

Or post #12 from this thread


  • stryker66 likes this

#13 maverixsian

maverixsian

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 22 Jan 2020

Posted 01 June 2020 - 08:10 AM

Wow - that does look very familiar! Almost the exact same problem as I am having. 


  • bobzeq25 likes this

#14 stryker66

stryker66

    Mariner 2

  • *****
  • Posts: 232
  • Joined: 31 Jul 2018

Posted 02 June 2020 - 06:42 PM

I was looking to get a color one for my ASI1600MM and ASI294 seems to be the only sensor that matches the resolution but I changed my mind because of this unfixable flaw and got the ASI071MC which have a very good dark current and no ampglow whatsoever..



#15 AhBok

AhBok

    Mercury-Atlas

  • *****
  • Posts: 2,649
  • Joined: 02 Dec 2010
  • Loc: Lakeland, TN

Posted 03 June 2020 - 07:21 AM

I was one of the contributors to the old thread. My ASI294MC had this problem. I worked with ZWO for a couple of months trying every combination of exposure time, temperature setting, gain, etc. and nothing worked to fix the problem. In the end, I returned the camera under warranty and purchased an ASI071MC Pro.

 

If you purchased your camera new, there is clearly a problem and should be returned. If your camera was from the early run that plagued many of us and is no longer under warranty, I do not know what to tell you.



#16 maverixsian

maverixsian

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 22 Jan 2020

Posted 03 June 2020 - 11:52 AM

I was one of the contributors to the old thread. My ASI294MC had this problem. I worked with ZWO for a couple of months trying every combination of exposure time, temperature setting, gain, etc. and nothing worked to fix the problem. In the end, I returned the camera under warranty and purchased an ASI071MC Pro.

 

If you purchased your camera new, there is clearly a problem and should be returned. If your camera was from the early run that plagued many of us and is no longer under warranty, I do not know what to tell you.

I purchased it new. So I think I will do the same and am working with the shop I bought it from. Thank you. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics







Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics