Ic2599

[TrevorW]

Different gain offset in this image for the ZWO1600GT, have been using 139/50 temp -10, tried 75/30 this time and decreased temp to -15c


5hrs data 3 Ha in 120s subs 40min each RGB in 30s subs


Bortle 7 skies



Scope Orion EON110ED


Stacked and processed in SIRIL and PS

[Startrek]

Trev,
Glad your getting some clear sky time over in the West.
From this latest image I don’t think changing the Gain from Unity 139 to 75 to provide a wider dynamic range at the expense of slightly more read noise, has provided a great deal of difference but only my opinion. I’d leave offset at 50 to give you a safe pedestal so as to avoid clipping. Also -10C is more than adequate for this camera in relation to dark current or dark noise.
I have no idea about Siril but the image colour ( pinkish / salmon ) of your recent batch of images is typical of one using a Mono data set with Ha substituting the Luminance channel ( in other words HaRGB not LRGB with a Ha Accent ) The Ha will be dominant and wash the RGB during colour calibration and colour balance ending up with that annoying pinkish salmon colour or slight reddish salmon colour. Stars will also lose true RGB colour and end up similar.
I also noticed diffraction spikes on the large stars ? Does the Orion refractor cause these optical anomalies ?
Have you tried ASTAP yet to stack your data sets ?
Hopefully other folk can jump in to offer more advice with the ZWO 1600 and the processing software Siril especially colour channel compositing and colour calibration and balance.
Cheers
Martin

[TrevorW]

Thanks for the feedback Martin, the diffraction spikes where added using a PS plugin, usual process is the add Ha as a layer in PS.

[TrevorW]

Did a bit of a reprocess

[RodW]

Hi Trevor

I've been using Siril for about 18m now and I'm still a beginner but have found the following approach works for me.

Using the RGB Compositing script, add your RGB channels as normal.
Then click the + to add another colour. This appears as yellow but can be changed. Insert your Ha stack here and then click on the yellow tile which opens a new menu and here you can select the colour wavelength as Ha. The yellow tile now changes to a red colour, typical of Ha.

Next run photometric colour calibration and see how it looks. It might look a little overly red but this can be adjusted later.
You can do the same process for adding Oiii and Sii and again select the correct colour wavelength for each.

Of course prior to all this you must run the conversion script and registration to perfectly align you RGB and Ha stacks so they can then been colour combined.

See how this goes. It works well most of the time for me.

Cheers

Rod W

[TrevorW]

Thanks Rod :)