Hystogram Stratching with Live Stacking of the Sun

[paolospeggiorin]

Hi! I,m a new entry.
I take public astronomy lessons at the public observatory of Specola Chiavacci in Pieve del Grappa, Italy.
We have a Coronado telescope to observe the sun, and we are collecting its images with a camera ZWO (ASI 178MC), projecting live images into a big wall monitor.
My question is the following: is it possible to show the sun details of prominances and cromosfere both at the same time?
I checked it is not possible with a single shot, due to the big difference in light levels of these different reagions.
I also tried using live stacking, and working on the hystogram stretching, but the controls of the stretching are not sufficient.
I know that the software ImPPG gives a very powerful tool to stretch the hystogram, with many control-points along the transformation curve (see attached Image).
I dream the possibility to apply this stretching technique to the Live Stacking process, in order to show live a very powerful image of the sun!
Can you suggest me anything similar ? Thanks a lot!

[admin]

Hi,

the best option for this is to run the camera in high bit depth mode (MONO16/RAW16) and then to use the display stretch function built into SharpCap. With a bit of tweaking you should be able to get some visibility on the prominances as well as keeping a reasonable view of the disc features, although neither will be as good as if you captured them separately. See https://docs.sharpcap.co.uk/4.0/#!2!Min ... %20Stretch for more details on the display stretch function.

Live stacking isn't really a good fit for this problem as it is designed around slower frame rates and aligning each frame based on star detection.

cheers,

Robin

[paolospeggiorin]

Thanks Robin!
I agree your suggestion are the best option at today stage.
But what I'm asking is : is it possible to add in Sharpcap an "Hystogram Curve management" like the one used in ImPPG software?
I think this should be sufficient to view in the proper way both low and high luminosity reagions with only one shot, that means you could show the benefit during live-view with people watching all around...

[admin]

Hi,

yes, in theory it's possible to have more complex histogram curves, I have had similar requests for more flexibility in the histogram stretch for live stacking, so this is something I might consider for SharpCap 4.2 or some other future version.

cheers,

Robin

[paolospeggiorin]

Thanks a lot for all your efforts!