[SOLVED] LiveStack does not stack frames

Discussions of Electronically Assisted Astronomy using the Live Stacking feature.
Hans-Heinrich Wenk
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[SOLVED] LiveStack does not stack frames

Post by Hans-Heinrich Wenk » Mon Apr 09, 2018 10:37 am

Hello,

I m using Sharpcap Version 3.0.4076.0 together with a ZWO-ASI174MM camera. A great software - congratulationes!
The frames I get are ok but with LiveStack I do not get the result i intend.
The problem is that Sharpcap seems to stack the frames but the resulting imaged does not progress when LiveStack is building.
Please have a look at the images attsched. No matter if the numer of stacked frames is 1, 2, 3 or 4 - the resulting image is always the same.
Am I doing something wrong?

regards
Hans

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Re: LiveStack does not stack frames

Post by admin » Mon Apr 09, 2018 12:50 pm

Hi Hans,

no attachments to look at - perhaps they got lost when you posted?

Robin

Hans-Heinrich Wenk
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Re: LiveStack does not stack frames

Post by Hans-Heinrich Wenk » Thu Apr 12, 2018 2:40 pm

Hi Robin,
thanks for your immediate reply and sorry for my delay ...
I now try to attach 3 versions of the stacked frames. Obviously I can only attach max. 3 files so I do not send the version with 3 stacked frames.

Hans
Attachments
Stack_4frames_40s.jpg
4 frames stacked
Stack_4frames_40s.jpg (212.64 KiB) Viewed 627 times
Stack_2frames_20s.jpg
2 frames stacked
Stack_2frames_20s.jpg (316.8 KiB) Viewed 627 times
Stack_1frames_10s.jpg
first frame
Stack_1frames_10s.jpg (403.75 KiB) Viewed 627 times

Hans-Heinrich Wenk
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Re: LiveStack does not stack frames

Post by Hans-Heinrich Wenk » Thu Apr 12, 2018 2:44 pm

Additionally the settins for Stack_4frames_40s
Attachments
Stack_4frames_40s.png.CameraSettings.txt
(593 Bytes) Downloaded 22 times

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Re: LiveStack does not stack frames

Post by admin » Thu Apr 12, 2018 4:04 pm

Hi,

look in the 'Alignment' tab of the live stacking UI and see how many stars it is detecting - good reliable results usually need 10+ and I'm wondering if that is the problem. Also the 'log' tab may show useful information about why stacking isn't happening. If none of that helps, please send

* screenshots of the live stacking UI area
* SharpCap main log
* anything error like appearing in the live stacking log.

Please also do this with the latest build of SharpCap 3.1

thanks,

Robin

Hans-Heinrich Wenk
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Re: LiveStack does not stack frames

Post by Hans-Heinrich Wenk » Sun Apr 29, 2018 12:48 pm

Hello Robin,

I have now switched to SharpCap Version 3.1.5143.0.
Stacking seems to work better now, especially if I do not subtract dark frames. In many cases I can now see the image-details growing (and the background getting brighter). Sometimes it seems there is no stacking (though the frames are not dropped) but maybe this is a problem of Digital Gain (Allignment Tab) being too low or off.
The situation is different if I stack frames subtracting a dark frame: I always see changes in the histogram but the stacked image often does not refresh. Switching "Subtract Dark" to None, then waiting for the next frame and finally switching back to dark frame subtraction sometimes helps and there are then visible changes with every new frame. This switching the dark frame off and on again seems to trigger a kind of refresh internally ... Anyway, the background of the stacked image gets darker (is this ok in case of using a dark?) with every new frame then. After adapting the histogram I see that the stacked image shows more and more details.

Problem 1: this switching to None and back again causes at least one stacked frame showing hot pixels
Problem 2: this method does not always help (but I have not yet found a real pattern)

I of course know, that these problems may arise because I do not use the software correctly!
If I know the pattern I will report this here!

Anyway, I like your software and will purchase a pro-License today!


Regards
Hans

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Re: LiveStack does not stack frames

Post by admin » Sun Apr 29, 2018 12:58 pm

Hi Hans,

good to hear you are making progress. When you have some time, please share one light frame and one dark frame with me in FITS format (the files will be too large to upload here - maybe put them in dropbox and share the link?). I can then look to see if I see the same results as you.

Another thing to ask - what is the specification of the computer that you are using? I am wondering if you are using a low spec (compute stick type) PC, which might struggle with the extra load of dark subtraction..

thanks,

Robin

Hans-Heinrich Wenk
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Re: LiveStack does not stack frames

Post by Hans-Heinrich Wenk » Sun Apr 29, 2018 1:58 pm

Hi,
concerning my computer. It is a standard midi-tower, one year old, Intel Core i5-6400 4x2,7 GHZ, RAM:16 GB DDR4, Nvidia GeForce GTX1050 with 2 GB,
OS: Windows 10 Home x64

The files you request I will send in a few days, hopefully with a more precise failure pattern!

regards
Hans

Hans-Heinrich Wenk
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Re: LiveStack does not stack frames

Post by Hans-Heinrich Wenk » Tue May 01, 2018 12:45 pm

Hi Robin,
good news!
With Version 3.1 you have implemented the Auto Stretch functionality for the stacked images. A very good new tool! Using it, I can now see, that stacking is always performed. I was simply expecting the wrong behaviour of your stacking mechanism, thought, that the observed objects should become brighter with every stacked frame (I am a beginner in astrophotography). Now - with Auto Stretch - I see, that stacking works more subtle, the image becomes smoother, shows more and more details and the background darkens step by step.
Subtractiong dark frames also works!

Thanks for your help!

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Re: LiveStack does not stack frames

Post by admin » Tue May 01, 2018 4:25 pm

Ah, that's good to hear. You are correct that the stacking doesn't really brighten dim objects because the final image shown is always stretched up to the same brightness range, instead it gradually reduces the noise. What you may find is that after a number of frames have stacked and the noise is lower you may be able to increase the amount of stretch applied to pull out even more detail without the noise being a problem.

cheers,

Robin

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