Very poor stacking results...

Somewhere to ask questions about the best way to use SharpCap
descott12
Posts: 32
Joined: Mon Dec 17, 2018 2:32 am
Location: Charlotte, NC USA

Re: Very poor stacking results...

Post by descott12 » Sun Jan 06, 2019 4:00 pm

Hello all,
Your feedback has really helped. I got a Bahtinov mask and a motofocus and that really helped. I have also learned alot more abuot using the histogram.
Attached a my latest M42 (19 minutes, gain about 200, exp 5-10 seconds), M31 (8 minutes, gain 200, exp 5 seconds) and a view of my Bahtinov focus image. I didn't use the focus tool in SC. I just changed to focus with the exposure at about 500 ms and watched the image improve.

Still a long way to go but it is nice to see an improvement so quickly
Attachments
M42_00001_WithDisplayStretch.png
M42_00001_WithDisplayStretch.png (435.67 KiB) Viewed 241 times
bahtinov.png
bahtinov.png (761.37 KiB) Viewed 241 times
small.png
small.png (672.6 KiB) Viewed 242 times
Last edited by descott12 on Sun Jan 06, 2019 4:13 pm, edited 1 time in total.

descott12
Posts: 32
Joined: Mon Dec 17, 2018 2:32 am
Location: Charlotte, NC USA

Re: Very poor stacking results...

Post by descott12 » Sun Jan 06, 2019 4:11 pm

Since this was somewhat unrelated to the original thread's topic, I removed the photos and started a new thread for this post. Unfortunately,
this post cannot be deleted...
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A few more learning opportunities that I am hoping you can help with.

1. In the M42 screenshot, the histogram looked good until about 16 minutes then a hump developed at the left side that I kept having to clip off my moving the black level to the right. Note also the bluish background tinge. My focus appears a bit off at that point but I think clouds had rolled in. What is the cause of the hump and is that related to the background bluish coloration? I seem to have that issue in most of my stacks. The background is not black but usually has blue tinge.

2. Running man - The color balance was way off and I noticed that the RGB peaks were not overlaying as I think they should. Should they pretty much overlay? and if yes, what causes them to diverge? I tried using the auto-color correction buttons but they often made it worse or caused the problem to begin with. Adjusting the vertical RGB sliders really didn't have the effect I wanted and a very small decrease in blue, for example caused the image to turn alien green.

3. There are three histograms
> The one used during live stacking
> The one in the lower right corner
> The one that you get to from the tool bar that has the Brain

They seem to have subtly different effects. Are they intended for different uses? I know the main menu one is only available when not live stacking.

Thanks in advance
Last edited by descott12 on Tue Jan 08, 2019 3:09 pm, edited 4 times in total.

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turfpit
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Re: Very poor stacking results...

Post by turfpit » Sun Jan 06, 2019 7:14 pm

Dave

Glad to see it is progressing for you now.

Time to look more at your settings. Try this
  • Set gain, brightness, exposure as per one of your images above..
  • Set Colour space=RAW16, Output Format-FITS
  • Turn on the Histogram from the toolbar and check the log box.
  • Capture a single frame.
  • Upload a screenshot of the loaded FITS frame, SharpCap screen, camera settings file.
You are aiming for a histogram which looks like Deep Sky - Logarithmic at https://docs.sharpcap.co.uk/3.2/#Using% ... %20Quality

Have a look at www.astrobin.com and put your camera into the Search at the top. Note the settings used from images you like.

Check here https://starizona.com/tutorial/hyperstar-images/ for your scope. Note the settings used.

Look in the SharpCap Gallery - you should find postings from @mAnKiNd and @BlackWickett helpful.

According to Starizona's website, the Hyperstar info an F10 scope is converted to f2 and can capture data 25 times faster. You will need to allow for that.

I am sure some experienced Live Stackers will be along to offer useful advice.

Dave

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