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Blue bubble stars

bodon
2022-10-02
2022-10-25
  • bodon

    bodon - 2022-10-02

    GDay all.
    Can someone help in regards to settings please. I use a ZWO 183 pro coloured camera. I use default settings in ASTAP and I tick "convert OSC images to colour" box only under stack method tab. I have used Sigma clip average for stack method, and under De-mosaic method astro simple but I still get blue bubbly stars. AstroM white stars works but surely I dont have to use this setting? I would like to keep the colours. No use fooling with any other setting as I dony understand them. Apprciate some assistance. I attached a jpeg to give you a heads up. Ta Regards

     
  • Grimstod

    Grimstod - 2022-10-05

    I actually get these to. But I export my images as 32bit Tiff files unstretched and strecht them in photoshop and that has avoided the issue.

    That said though there should be a solution to this.

     
  • bodon

    bodon - 2022-10-06

    I see Im not the only person then...Yup I do the same and export into siril or PS. Still Id like to play with the pic Astap shows. Pain in the backside.

     
  • Grimstod

    Grimstod - 2022-10-06

    I am surpirsed that Han has not stepped in. He must be on vacation or something.
    I will try a few things today. If I can figure it out ill let you know.

     

    Last edit: Grimstod 2022-10-06
  • Grimstod

    Grimstod - 2022-10-20

    These might have something to do with Photometric Color controls. I have never messed with that though and always just did the stacking part only.

     
  • han.k

    han.k - 2022-10-20

    I was two weeks away.

    Getting good coloured stars is always difficult. The problem is that bright stars typically saturate the sensor in seconds. The center of the star is recorded as white because all channels reach values near 65535.

    An other problem is that stars are a few pixels in diameter. This will cause unequal illumination for some RGGB pixels.

    ASTAP tries to recover the star center colour by reconstructing the center colour from the outer regions and smoothing the star colour. This smoothing is adjustable with setting "Colour smooth". You can increase the diameter from 10 to 15. Secondly you can experiment with de-mosaic methods AstroC, AstroSimple and SuperPixel.

    In general using short exposure times helps to avoid most star saturation. Something like 30 seconds. not much longer.

    Han

     
  • han.k

    han.k - 2022-10-20

    I forgot attach the screenshot:

     
  • Grimstod

    Grimstod - 2022-10-25

    Thanks Han. I knew ther had to be something. I will experiemnt with this today.

     

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