SharpCap Forums

Hi Robin,
I have written and successfully executed my script to LiveStack 20x30s lights without debayer, dither and repeat 60 times to give me 60 x 600s lights subs. Now onto making my darks....
I would like to know if my dark frames are without any processing to make them non-linear, and without any other processing. I am using the ASI2600MC.

I know the darks match my lights because in my darks creation sequence I only cancelled monitor guiding and dithering. But I want to know if there is any processing? I ask because when I review the captured CameraSettings.txt it has these lines:
LiveStack.SigmaClipInitialCount=5
LiveSack.SigmaClipThreshold=3
LiveStack.SigmaClipLowLimit=1
also,
LiveStack.BlackLevel=0
LiveStack.WhiteLevel=100
LiveStack.MidLevel=25 (why not 50, and is this affecting my livestack file?
and
AutoStretch.Strength=2 (My sequence says DISPLAY STRETCH RESET).

My sequence and camerasettings.txt files for darks are both attached. Does anything look amiss in these files?

To review my goals:
-- Capture LiveStack 20x30s = 600s lights subs (no debayer) and save this file. Repeat 30 times.
-- No debayer, no align, no rejection, no stretching of saved file.
-- Matching LiveStack 10x30s = 600s dark frames.
-- Calibrate in PixInsight with WBPP creating master dark, master flat dark, and master flat. Continue processing in PI for registration, integration, noise reduction etc.

Many thanks for your review and advice!

Roger

Hi Roger,

I can't see anything obvious in there that would cause non-linear behaviour, although you do have some of the filtering turned on in the live stacking settings (I think that the filters will not be enabled because alignment is turned off, so no stars get detected though).

I hope it works out OK for you - I do worry a bit because it's not really designed with this sort of approach in mind, so there could be things lurking in the stacking code that I have forgotten about that might cause issues...

cheers,

Robin

Hi Robin,
Yes, I know I am using the software differently than your intention. I want to try this and see if I can get better results than my previous series of 600s too long subs.
For your statement:
... you do have some of the filtering turned on in the live stacking settings....
Do you mean the tabs along the top of the histogram which include FWHM and Brightness filters? I kept these 2 filters 'on' to cancel subs with clouds or other problems.
In my sequence I believe the histogram was reset as my sequence has these commands: LIVE STACKING STRETCH RESET. As I recall, the transfer curve was not a straight line, but lifted up some at left side. Does this mean the raw image was processed before live stacking? I saved my stacked image as 16bit Fits file.

Thanks,
Roger

Hi Roger,

so for the filtering, I was just pointing out that perhaps they should be turned off for the dark frame capture (but in practice I don't think it will matter).

For the stretch, the default (reset) stretch in live stacking is not a linear one - it's a fairly weak stretch that brightens the shadows and mid tones when displayed on screen. However, that stretch does not affect the data saved to a 16 bit file - only when saved 'with adjustments' or 'exactly as seen'.

cheers,

Robin

Hi Robin,
No questions for you in this message..
Thanks for the discussion for saving darks. Since there are no stars with dark frames, the FWHM filter does nothing, and the brightness is very uniform frame to frame. So I agree these filters do not matter for the darks.

I reached the same conclusion today that my livestacks are linear and pure as I am saving as 16 bit fits, and not as 'with adjustments' or 'exactly as seen'. I went through all the histogram/controls tabs and everything is turned off (like sigma clipping) except the FMWH and Brightness filters.

Thanks and I will continue with gathering my lights.

Roger