The grid is the pixelmatrix. Don't zoom in that much
Colours get real after colorcalibration.
Raw 16 is the right one. Then you have 16 bit per pixel that means you get the (chip origin)12 bit multiplied by 4 in the files. These files must be debayered.
RGB 24 means 8bit per colour, you get a ready coloured picture (the cam debayers it for you) but the dynamic is compressed to 8bit.
The ampglow of this chip is caracteristic for it. It even got named "starburst" glow. The glow gets stronger with exposuretime but can be calibrated out well with darks.
The darks must suit well: Same temperature and exposuretime is essential. Also avoid long exposuretimes (not more then 5min).
There is a really long thread on cloudinights about this as I mentioned before. Google for "IMX 183 starburst jon rista cloudynights".
this doesn't seem to be readoutnoise - it's ampglow. Why one shows it and the other not I can't say but it only should be exposuretime dependant.
Amp glow described in the CN imx183 testthread here: www.cloudynights.com/topic/599475-sony-i...d-asi-qhy-etc/page-2
He did some improvements:
if dithering is active, does the sequencer wait for settling after dithering between exposures or must this be done by delay time?
Or is the guidemodule sending some "dithering performed and settled" signal for the sequencer is listening to? Is it like this with external guiders?
If one session of ekos is mastering the guider and scope and other sessions just listen to that guider saying "dithering ok", than the sessions would be synced and multicamera operation was easy.
This is the cause of your "undithered" looking capture. Asuming pixelsize is nearly identical on both cams you dithered your main cam 2.8*1000/1200=2.33 pixel.
This is near nothing. Hot pixel or "ununiform behaving" ones are neighboring themselfs in the stack, this makes the rain fall.
Dither at least 10-20Pix with this configuration to separate them for sure.
You should not see this misalignment (showing in noiserain) at all, if dithering went well. Maybe dithering was just not wide enough. How much pixel did you dither and what is the ratio between guide scope focal length and main scope focal length?
I think this is a misconception. Calibration frames like bias or darks might be clipped on the left side of the histogram with offset 0. This could introduce artifacts during calibration.
scroll down to "Anatomy of Signals in Histograms". The offset value prevents the "separation" of beeing negative.