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Blue cast after stacking
I have a problem with a blue cast after stacking. The strange thing is, that happens only when i add the secons stack.
Thats the result from session 1:
Then start a new stack with session 1 and session 2, and the result is this:
I use the same setup for both sessions, with the same settings. The single frames looks similar. So i try to stack only session 2, and it looks like this:
Camera was an ASI2600 MC Pro with the Optolong L-Pro filter. I use für both session 5min exposures at gain 100 at -10 degree. Thats a single frame from session 2. There is noting blue or purple like in the final stack.
Any idea what i have to check in the settings?
Dane, what settings did you use from tabs 0 to 6 for these stacks? Also, the single frame that you posted is not debayered and therefore is greyscale. That's why no blue or purple (or any other colors) are visible in it.
Hi Wouter, i use these settings:
Two questions. First of all, you really only have 4 lights? If yes then don't expect miracles because you'll need many more to get good colors. Secondly, why do you not use the automatic settings in tab 6?
the four images are only for test. I dont have a time machine to get back to the past before i startet the stack. So I just simulated the settings. I actually always set the same. But yes, it would be cool when i get these details with only 4 shots. 😀
I saw this once in a video where someone recommended the "average" and "quality" setting as a reference for which the best quality shots are preferred, if I understood correctly. But I have the feeling that if I set it to Automatic it does not change the colors?
I am not sure which video you refer to but possibly it is quite old. The Automatic setting was introduced so APP can determine the best settings for the stack itself. Please use that.
I will consider this in the future. But what about my actual problem?
What I meant was for you to restack with Automatic and tell us what you get.
i finish the stack now with the automatic setting:
And here is the result:
I dont used the tools at number 9.
Thanks. That at least reproduces the second stack that you posted in your original post. This then seems to indicate that there is a difference in the data between sessions 1 and 2. Could you please upload the data (I think we have sent you instructions before, right?) so we can have a look?
A thought struck me. Can you please check the ZWO driver settings used to take the images? ZWO introduced white balance offsets in their drivers which by default are set to WB_R = 52 and WB_B = 95. This could lead to too much blue in the images. If they are set to those defaults then please set them both to 50.
i never see the ZWO Drivers. I work with the ASIAIR.
How can i upload the data? I have a Dropbox Account where i can upload the data and send you the link.
ASIAir does allow you to configure the camera, doesn't it? There it should allow you to set the red and blue offset for the white balance. These are set to default values by the driver but should be allowed to be overridden by the user.
You can upload your data to
using user upload4 and password upload4 as well. Please create a directory dane-vetter-m31 and put your files inside that directory.
the upload is finished. I am curious what comes out of it. Thank you.
Hi Dane, I finally managed to download your huge amount of data. Thank you for the patience to upload that all!
I have first stacked all data in Session 1 and see nothing strange. This is a screenshot of the final stack:
I then first applied a crop to get rid of the edges:
Then I applied Remove Light Pollution:
Finally I enabled saturation:
Then I stacked all the files in Session 2. I didn't perform the same steps in post-processing but the raw stack looks like this:
As you can see, no suspicious blue hue at all.
Then I loaded all lights, flats and dark flats of session 1 into session 1 and the same for the files of session 2. Finally I loaded all darks and assigned them to all sessions. I left everything else at their defaults and went straight to tab 6 and clicked on Integrate. This is the raw stack that was produced:
It is clear that the camera was slightly rotated between the two sessions so I cropped a bit more than with session 1 alone:
Then I applied Remove Light Pollution again:
And finally enabled saturation:
This is a pretty good result to start from in further post-processing. As I explained before, once you have your final stack you will need to post-process it to get out all the nice colours and details and it is up to you to do that. One thing that you could consider is to reduce Red. Whether you do this in APP or another application is up to you.
However, to me it looks like your data are perfectly OK.
thanks for testing my data.
I added the lights, flats, darkflats from session 1 to session 1, and i added the lights, flat, darkflats from session 2 to session 2. I added the darks to all sessions.
Thats my result after the stack:
Removing the light pollution:
After i enabling the saturation:
There i a blue cast, but from where?
How is this possible? I cant believe it that you can stack the same data with the right colors, and im not? This drives me crazy!
I use the in all the settings the automatic. The only thing that i change is LNC Degree, enable MBB. But this settings should nothing to do with the colors when i understand it right.
First of all, in tab 1 there is no need to load both the raw flats, darks and darkflats and the masters. Just choose one of them and leave the others out.
Secondly, I see that you did not load the 30 s Lights while I did. I don't think it will make much of a difference but why did you not include them?
Finally, LNC may affect the illumination properties of the stack as is explained in the help. It should only be used by raw images that are affected by gradients in a different way. As you can see in the screenshots that I posted, this is not the case with your data.
So I'd suggest you disable LNC completely and try again.
Yes, to disable LNC was the solution!
I really did not believe that this could be the cause. In the description there is nothing mentioned about such a problem.
Is it generally useful to deactivate LNC always?
I immediately tried to add 9 more hours of H-Alpha. But I still have a lot to try in post processing and also work with the colours.
Thank you Woulter!
Glad we got that sorted. Regarding LNC, I already wrote that in my previous comment: as is explained in the help, it should only be used by raw images that are affected by gradients in a different way.