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Calibrate Star Colour help  

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(@tony-liu-photography)
White Dwarf Customer
Joined: 1 year ago
Posts: 11
August 12, 2018 06:56  

So I've done some reading on the topic through out the forum, but I am still not very sure at how to tackle this particular function

Here is a stack (with LP removal and BG calibration already applied) of the Veil Nebula I attempted last night, would someone be kind enough to run me through Calibrate Star Colour function with this?

https://www.dropbox.com/s/i6x6japgbv5aoxh/St-avg-1492.0s-NR-x_1.0_LZ3-NS-full-eq-add-sc_BWMV_nor-AA-RL-MBB5_1stLNC_it1-mod-lpc-cbg-cbg.fits?dl=0

Attached screenshot shows what it looks like after I had first applied calculation

Thanks in advance!

APP Screenshot

This topic was modified 7 months ago by tony.liu.photography

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(@mabula-admin)
Quasar Admin
Joined: 2 years ago
Posts: 2070
August 19, 2018 23:34  

Dear Tony @tony-liu-photography,

I have downloaded the data.

First of all, if you perform Light Pollution correction, Background calibration is done as well (changed some versions ago). You don't need to do Background Calibration separately after the Remove Light Pollution tool since it's done already 😉

This is what I get with the Star Color Calibration:

StarColorCalibrationSettings
StarColorCalibration

Please check this new video tutorial on star color calibration as well, it contains explanation on the parameters:

https://www.astropixelprocessor.com/part-5-star-color-calibration-of-the-mosaic-tutorial-milky-way-to-rho-ophiuchi-by-mabula/

Can you share the details of this data capture? It seems that you might have used an LP filter or not?

  • which camera
  • which filters if any
  • which telescope

Star Color Calibration in principle with the Black Body and Extinction model needs Broadband RGB data. If you use a LP filter, the initial settins need to be changed quite bit..

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@tony-liu-photography)
White Dwarf Customer
Joined: 1 year ago
Posts: 11
August 23, 2018 12:15  
Posted by: Mabula Haverkamp - Admin

Dear Tony @tony-liu-photography,

I have downloaded the data.

First of all, if you perform Light Pollution correction, Background calibration is done as well (changed some versions ago). You don't need to do Background Calibration separately after the Remove Light Pollution tool since it's done already 😉

This is what I get with the Star Color Calibration:

StarColorCalibrationSettings
StarColorCalibration

Please check this new video tutorial on star color calibration as well, it contains explanation on the parameters:

https://www.astropixelprocessor.com/part-5-star-color-calibration-of-the-mosaic-tutorial-milky-way-to-rho-ophiuchi-by-mabula/

Can you share the details of this data capture? It seems that you might have used an LP filter or not?

  • which camera
  • which filters if any
  • which telescope

Star Color Calibration in principle with the Black Body and Extinction model needs Broadband RGB data. If you use a LP filter, the initial settins need to be changed quite bit..

Mabula

hi Mabula thanks for the reply!

it is shot with a modified 760D (one of the low pass filters removed and replaced with baader clear glass) shot with sigma 135mm 1.8 art with STC astro-m LP filter in front, thanks!

Tony


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(@mabula-admin)
Quasar Admin
Joined: 2 years ago
Posts: 2070
September 25, 2018 20:53  

Hi Tony @tony-liu-photography,

Apologies for this late response ;-(

it is shot with a modified 760D (one of the low pass filters removed and replaced with baader clear glass) shot with sigma 135mm 1.8 art with STC astro-m LP filter in front, thanks!

You mean a filter like this : ?

https://www.cyclopsoptics.com/astronomy-filters/stc-astro-duo-narrowband-filter-48mm/

Star Color Calibration works best if you have broadband data. Such an LP filter will complicate star color calibration using black body physics. This means that you will need to be more aggresive with especially the slope parameters. They probably need to be much lower than the default values of 1.0 and 2.0. It can be as low as 0.4 and 1.0 depending on the filter and the used camera.

Kind regards,

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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