Equipment used:

  • Lumix G85
  • Lumix 100-300 f4-f5.6
  • SA-GTI

Image:

  • 10 sec, f/6.3, 6400 ISO
  • 1200 Lights
  • 50 Biases, Darks, Flats

Stacked using Siril and edited in GIMP

As you can see, there is a lot of noise, even with heavy editing and noise reduction in siril as well as in GIMP, and I’m out of ideas of what could cause it. I tried different exposures (from 10s to 30s), different ISOs (1600-6400). I tried to manually dither by moving the mount through the App every 30 minutes or so. I also used a lens dew heater at different temperatures ranging from 15°C to -5°C with no difference in noise.

I got a successful result a few months ago with the Orion nebula, the only differences were the exposure of 5 seconds and a Omegon Mount MiniTrack LX3 Essentials mount which couldn’t be polar aligned very well. I can’t imagine that the difference from 5 to 10 seconds exposure did all the difference.

Can anyone help me?

  • Zer0_F0x@lemmy.worldEnglish
    6·
    22 days ago

    Try longer exposures, your mount can do 30 sec easily with a 300mm lens, even without guiding.

    Also, go through your subs and remove anything that looks out of the ordinary. Better to have 600 good subs than 1200 with bad ones in the mix. Look for clouds and condensation mostly.

    This sort of noise increases the closer to the horizon the target gets. Stay above 30 degrees if possible.

    Check if your white balance is set to auto, if it is set it to something fixed.

    Lastly, judging by the end result you should try a less aggressive stretch, especially for the background. You can make a mask of the nebulous part, stretch it a lot and then use it as a luminance and saturation mask over a copy layer that has a neutralized, darker background.

    There’s lots of good signal in there, give it a go

    • Linsensuppe@feddit.orgOPEnglish
      1·
      22 days ago

      I tried imaging with 30 seconds exposure recently on the Andromeda Galaxy and got this result with almost identical noise:

      This was 315 subs at 30 seconds so around 2.5 hours of exposure.

      So just increasing the exposure did not do a difference.

      • Zer0_F0x@lemmy.worldEnglish
        2·
        21 days ago

        Check each channel individually. Are the noise levels and shapes different for red, green and blue?

        • Linsensuppe@feddit.orgOPEnglish
          1·
          21 days ago

          In the final .fit the Red channel has, as expected, the fewest signal, but also the most noise in the dark areas of the image.

          In the Raw subs I couldn’t make out a channel with more noise than another.