• lefty7283@lemmy.worldOPEnglish
    5·
    13 days ago

    Decided to just shoot a semi-random part of Cygnus. The large extended Ha region in Cygnus is unofficially called Smaug, and this is a photo specifically of the area around LBN 325/326. The nebulosity in this pic is false color, but the stars are true color RGB. I really love how this turned out with the narrowband palette, especially with the Oiii region on the right side looking almost like a true color Ha region. Captured over a shitload of nights from Aug-Oct 2024 from a bortle 9 zone.

    Places where I host my other images:

    Flickr | Instagram

    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: 57 hours 40 minutes (Camera at -15°C), NB exposures at unity gain and BB at half unity

    • Ha - 111x600"

    • Oiii - 127x600"

    • Sii - 94x600"

    • R - 48x60"

    • G - 48x60"

    • B - 44x60"

    • 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 (to be later replaced by the RGB ones)

    • HistogramTransformation to stretch nonlinear

    RGB Linear:

    • ChannelCombination to combine monochrome R G and B frame into color image

    • SpectroPhotometricColorCalibration

    • BlurXTerminator for star sharpening (correct only)

    • HSV Repair

    • StarXterminator to generate a stars-only image

    • ArcsinhStretch + HT to stretch nonlinear (to be combined with starless narrowband image later)

    • Invert > SCNR > invert to remove magentas

    • Curves to saturate the stars a bit more

    Nonlinear:

    • PixelMath to combine monochrome Ha Oiii and Sii images into a color image with Jimmy’s Royale Palette

    R = 0.3*Oiii+0.7*(Oiii^~(0.7*Ha+0.3*Sii))^1.2

    G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ((Oiii*Ha)^(Oiii*Ha))*Sii

    B = 0.9*Sii+Ha-Oii

    • NoiseX again

    • Shitloads of Curve Transformations to adjust lightness, hues, contrast, saturation, etc

    • more curves

    • Extract L --> LRGBCombination for chrominance noise reduction

    • even more curves

    • Pixelmath to add in the stretched RGB stars only 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))

    • Couple final curves

    • Resample to 60%

    • Annotation