• 11 Posts
  • 2 Comments
Joined 2 years ago
Cake day: July 13th, 2023
  • lefty7283@lemmy.worldOPMtoAstrophotography@lemmy.world•Sh2-173 in HSSEnglish
    3·
    12 days ago

    Another faint nebula from light polluted skies! Really like how the faint background dust in the Sii channel turned out in this. Captured over a bunch of nights from January-March 2025, from a bortle 9 zone.

    Places where I host my other images:

    Flickr

    Equipment:

    • TPO 6" F/4 Imaging Newtonian

    • Orion Sirius EQ-G

    • ZWO ASI1600MM-Pro

    • Skywatcher Quattro Coma Corrector

    • ZWO EFW 8x1.25"/31mm

    • Astronomik LRGB+CLS Filters- 31mm

    • Astrodon 31mm Ha 5nm, Oiii 3nm, Sii 5nm

    • Agena 50mm Deluxe Straight-Through Guide Scope

    • ZWO ASI-290mc for guiding

    • Moonlite Autofocuser

    Acquisition: 68 hours 4 minutes (Camera at -15°C), unity gain

    • Ha - 179x600"

    • Sii - 219x600"

    • R - 36x60"

    • G - 35x60"

    • B - 33x60"

    • Darks- 30

    • Flats- 30 per filter

    Capture Software:

    • Captured using N.I.N.A. and PHD2 for guiding and dithering.

    PixInsight Preprocessing:

    • BatchPreProcessing

    • StarAlignment

    • Blink

    • ImageIntegration per channel

    • DrizzleIntegration (2x, Var β=1.5)

    • Dynamic Crop

    • DynamicBackgroundExtraction

      duplicated each image and removed stars via StarXterminator. Ran DBE with a shitload of points to generate background model. model subtracted from original pic using the following PixelMath (math courtesy of /u/jimmythechicken1)

      $T * med(model) / model

    Narrowband Linear:

    • Blur and NoiseXTerminator

    • StarXterminator to completely remove stars from each the image

    • HistogramTransformation to stretch Ha and Sii images to nonlinear

    Broadband/RGB linear:

    • ChannelCombination to make color image from R G and B stacks

    • SpectrophotometricColorCalibration

    • HSV repair to fix blown out star cores

    • StarX (correct only)

    • StarX to make a stars only image

    • ArcsinhStretch + Histogramtransformation to stretch nonlinear (Calling this the Stars image now)

    • SCNR > Invert > SCNR (50%) > Invert to remove greens and some magentas from stars

    • Slight saturation boost

    Nonlinear:

    • Pixelmath to combine stretched narrowband images into color image (HSS --> RGB)

    • Shitloads of curve transformations to adjust lightness, contrast, saturation, color balance, etc

    • ColorSaturation

    • NoiseXterminator

    • Pixelmath to add in the stretched RGB Stars image from earlier

      This basically re-linearizes the two images, adds them together, and then stretches them back to before. More info on it here)

      mtf(.005,

      mtf(.995,Stars)+

      mtf(.995,Starless))

    • few more curve adjustments

    • DynamicCrop again (just a little bit)

    • Resample to 60%

    • Annotation

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