Author Topic: Help with this mess?  (Read 3369 times)

Offline bjgiii

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Help with this mess?
« on: 2014 December 23 06:07:57 »
This is a stack of 65 lights, darks and bias frames using DSS and shot with a modified dslr. I'm new to processing in general. Pixinsight is all I've ever used. What is the vertical banding in my image? This is a quick stretch and one pass of DBE.  I've been using a tutorial from light vortex astronomy and seem to lose a lot of color when completing the work flow. Also, is it necessary or best to create a Luminance image and process it separately using OSC?

Offline NGC7789

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Re: Help with this mess?
« Reply #1 on: 2014 December 23 06:27:20 »
This is typical Canon banding. Try the Canon banding script to remove it.

Offline bjgiii

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Re: Help with this mess?
« Reply #2 on: 2014 December 23 06:57:17 »
Where do I find the script? Thanks

Offline MortenBalling

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Re: Help with this mess?
« Reply #3 on: 2014 December 23 08:00:39 »
Script tab > Scripts > Utilities > CanonBandingReduction  ;)

Offline Alejandro Tombolini

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Re: Help with this mess?
« Reply #4 on: 2014 December 23 11:34:54 »
Hi, welcome to the forum.

It seems like your subs has a short exposure time. Could you provide that info and how many bias and darks did you use to genereate the masters?
I recomend that you make a try using BatchPreprocessing to integrate your image. See this processing expample as guide. Using a SuperBias could be helpful in this case.

Also see the following videos about using BatchPreprocessing:

Add Bias
Add Darks
I assume that you do not have flats
Add lights
Select Reference image for registration
Select output directory
Check CFA
Diagnostics
Run the script

Hope this helps

Saludos, Alejandro.

Offline bjgiii

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Re: Help with this mess?
« Reply #5 on: 2014 December 23 12:24:21 »
I used 65 lights, darks and bias frames. No flats. This was shot with a Canon T3i with a full spectrum mod. I also used a astronomik UV/IR filter. They where short exposures. 120s @ ISO800. I image near a red zone, so that was as long as I could go.

Offline pfile

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Re: Help with this mess?
« Reply #6 on: 2014 December 23 13:45:37 »
you might try 240s @ iso400 or even 480s @ iso200. the read noise is higher at those ISOs but it's worth a try. the sky signal is going to dominate everything anyway, and the only way to get more DSO photons is to expose longer.

an astronomik CLS filter will work against this type of target, you could probably double your exposure time at the same ISO with one of those.

rob

Offline bjgiii

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Re: Help with this mess?
« Reply #7 on: 2014 December 23 14:05:37 »
Rob,

I have cls filter as well. I was shooting M45 earlier in the night and didn't have it in. Its my understanding that reflection nebula are a little touchy with a cls filter. I will try and shoot at a lower iso to increase exposure time.

Offline pfile

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Re: Help with this mess?
« Reply #8 on: 2014 December 23 15:46:42 »
indeed the CLS filter is bad for reflection nebulae, and galaxies. i have however employed one for both targets, just to see what would happen.

http://www.astrobin.com/14275/

the color balance there isn't quite right and i really needed some shorter exposures for star color, but i guess if you want to put in ridiculous amounts of integration time it is possible to get a halfway decent result of a reflection neb even with the CLS. the trick in that image was that i took ferran bosch's very deep image (http://www.astrobin.com/8179/) and re-registered it to mine. i placed the DBE samples on his image since it's abundantly clear where there is background and where there is signal. then i saved the process icon and applied it to my image. anyway i believe my results would have been impossible without the various processes that PI gives us (and a good reference image :) )

rob