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?
It could also be that you’re not dithering often enough. Dithering every 30 mins means you’re taking 180 frames before each dither and that’ll really let the walking/raining noise build up. you could try doing 30" subs and then dithering every ~10 minutes if that’s practical? For me personally I dither after a max of 5 subs (or dither after a sequence of something like LLLLRRGGBB) , but I know I’m also taking longer exposures and have the benefit of automation.
Personally I’ve never used a GTi or Lumix camera, but if you’re able to hook them to a computer with NINA, there is an option to have it dither automatically even without an autoguider
AFAIK NINA doesn’t work with my camera, but since my mount is within Wi-Fi reach of me, I can move the GTI through the app slightly from inside. My question with that is, how much do I have to/should I dither? Currently, I move the stars so that there is a significant jump on the SLR screen, so I would guess it’s a few hundred pixels in x and y direction.
Few hundred pixels is definitely enough, and kinda overkill (mine goes a few dozen). I think the frequency of the dithers is probably the main thing that could help with the noise