Flat field usb problem

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Fabio F.
Posts: 12
Joined: Sun Sep 08, 2019 11:52 am

Flat field usb problem

Post by Fabio F. » Sun Sep 08, 2019 12:13 pm

The first flat is acquired correctly.
The second or third presents the problems shown in the image.
For a good flat I have to restart the software.

- I tried all the usb sockets (USB2 USB 3) on the computer
- I used the original cable and other cables
- I tried to change all sharpcap usb settings

- WINDOWS 10
-SHARPCAP 3.2.6097.0
- ZWO ASI 294 PRO
- COMPUTER ACER EX2530

How can I solve this problem?
Thank you.
Attachments
flat degradazione.png
flat degradazione.png (470.73 KiB) Viewed 290 times

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admin
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Re: Flat field usb problem

Post by admin » Sun Sep 08, 2019 8:14 pm

Hi,

I have the same camera and don't recall seeing this problem. Please could you let us know the exact steps that you took to capture these images (including what settings were used to capture them). It would also help to have copies of the captured flat frames and the camera settings files that SharpCap creates next to them to be able to investigate this properly.

Cheers, Robin

Fabio F.
Posts: 12
Joined: Sun Sep 08, 2019 11:52 am

Re: Flat field usb problem

Post by Fabio F. » Mon Sep 09, 2019 8:55 am

Attached the settings I used for the master flat.
The first flat is good, the third is not good.
The settings for the three flats are the same.
If I restart the software the first flat is good.

The original master flat is too big to load (17.9MB).
Can I send them in any other way?


Thank you.
Attachments
flat degradazione.png
flat degradazione.png (470.73 KiB) Viewed 272 times
impostazioni master flat seconda pagina.jpg
impostazioni master flat seconda pagina.jpg (184.69 KiB) Viewed 272 times
impostazioni master flat.jpg
impostazioni master flat.jpg (162.5 KiB) Viewed 272 times

BlackWikkett
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Re: Flat field usb problem

Post by BlackWikkett » Mon Sep 09, 2019 2:38 pm

I also have the ASI294 and have not encountered this issue. From your images I see your using SER format. I'm not sure but I think the flat capture defaults to fits. If it doesn't this may be something to check. In my flat process I usually changes this to fits. Also have a look at your Turbo USB setting. You have auto enable and it's set to 80 currently. I turn of auto and set 40 for Turbo USB.

Fabio F.
Posts: 12
Joined: Sun Sep 08, 2019 11:52 am

Re: Flat field usb problem

Post by Fabio F. » Mon Sep 09, 2019 3:27 pm

Also with 40, the result is the same.
The flat is recorded in .png format.
I tried several different Turbo USB settings with the same results.

Fabio F.
Posts: 12
Joined: Sun Sep 08, 2019 11:52 am

Re: Flat field usb problem

Post by Fabio F. » Mon Sep 09, 2019 4:44 pm

The same test performed with version 3.1
Attachments
impostazioni 3.1.png
impostazioni 3.1.png (133.08 KiB) Viewed 257 times
3 flat sharpcap 3.1 ingrandmento.png
3 flat sharpcap 3.1 ingrandmento.png (244.09 KiB) Viewed 257 times
3 flat sharpcap 3.1.png
3 flat sharpcap 3.1.png (877.77 KiB) Viewed 257 times

Fabio F.
Posts: 12
Joined: Sun Sep 08, 2019 11:52 am

Re: Flat field usb problem

Post by Fabio F. » Mon Sep 09, 2019 5:16 pm

The three images of the first test displayed with Gimp 2.10
Attachments
gimp 3.png
gimp 3.png (258.44 KiB) Viewed 256 times
gimp 2.png
gimp 2.png (284.89 KiB) Viewed 256 times
gimp 1.png
gimp 1.png (344.74 KiB) Viewed 256 times

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admin
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Re: Flat field usb problem

Post by admin » Mon Sep 09, 2019 6:35 pm

Hi,

I'm afraid that it's difficult to tell anything where you've posted the screenshots of the files open in an image viewing application – downloading the raw files and the capture settings files that go with them is essential to be able to diagnose this issue properly. You may find that the image files are too large to be uploaded to the forums, in which case consider uploading them to a file sharing website like dropbox and sharing a link to download the files.

Cheers, Robin


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Re: Flat field usb problem

Post by admin » Tue Sep 10, 2019 6:27 pm

Hi,

That's really weird. It looks like for some reason there are dark pixels in some of those images, although they are not completely black.

I wonder if you are intermittently getting bad frames come through from the camera (with unexpected black pixels in them) and the averaging process in the flat creation routine would then mean that those black pixels would not be completely black because they would only be incorrect in one frame out of 20 or so. It would be worth testing with a reduced number of frames being averaged in which case you would expect the problem to happen less often to be worse when it does happen if this idea is correct. You would also expect to see the occasional black pixel or dark pixels in normal frames.

I'd also suggest updating to the latest version of SharpCap – you seem to be using an old version because the option to subtract bias frames from the flat is not present in the capture flat window.

I've just tested creating a monochrome flat frame from 20 individual frames on my ASI 071 camera (which is as close as I have your model) and I don't see any similar problems.

Cheers, Robin

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