Strange Bias on Atik460EX

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Strange Bias on Atik460EX was created by Gebhard

Hi,
I am testing my ccd with indi and took 50 bias frams at -10°C at 0.01sec exposure time. The mean and the median of these biases show a stable cross of about 10 counts over the rest of the image plane. Doing the exposures with artemis.exe there is no cross but other features in the mean bias of my Atik 460EX. The different frame sets are equally processed with eso-midas.

Tests with an Atik 420 from a friend produce equal biases form indi and artemis.

Whom should I trust? I did two series with indi at different days. the meanbias always show the cross feature.
Strange.

cherno
8 years 2 months ago #9028
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Replied by Peter Polakovic on topic Strange Bias on Atik460EX


Rendering Error in layout Message/Item: array_keys(): Argument #1 ($array) must be of type array, null given. Please enable debug mode for more information.

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Replied by Gebhard on topic Strange Bias on Atik460EX


Rendering Error in layout Message/Item: array_keys(): Argument #1 ($array) must be of type array, null given. Please enable debug mode for more information.

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Replied by Peter Polakovic on topic Strange Bias on Atik460EX

Hmmm, if the only difference will be the additional horizontal line I can imagine, that the issue is max packet size. Default value is 8MB and total transfer is 12MB in case of 460. This artifact is in 1/3 of the image and it is not clear if the image is flipped or not. This looks suspicious, it is worth to try to increase packet size. I'll make new build and let you know.

What puzzles me is that also vertical line looks different... If you are using different machines for tests linux vs. windows, it also possible, that 460 is more sensitive than 420 for something related to USB controller on this notebook. Peter
8 years 2 months ago #9048

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Replied by Gebhard on topic Strange Bias on Atik460EX

Vertical lines are the same on all three machines involved. But image captured on windows machines are flipped compared to the indi frames. But that doesn't matter.

cherno
8 years 2 months ago #9049

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Replied by Peter Polakovic on topic Strange Bias on Atik460EX

OK, I'll make new build tonight. Peter
8 years 2 months ago #9052

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Replied by Peter Polakovic on topic Strange Bias on Atik460EX

Hi cherno, can you try this version (with 16mb buffer size):

download.cloudmakers.eu/atikccd-1.3-i386.deb
download.cloudmakers.eu/atikccd-1.3-i386.rpm
download.cloudmakers.eu/atikccd-1.3-amd64.deb
download.cloudmakers.eu/atikccd-1.3-amd64.rpm

Thank you, Peter
8 years 2 months ago #9068

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Replied by Gebhard on topic Strange Bias on Atik460EX

Perfect!
The horizontal line is gone.

You've done a great job.
Thank you very much!
cherno
8 years 2 months ago #9077

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Replied by Gebhard on topic Strange Bias on Atik460EX

Sorry to say. The horizontal line is back at row 1527. I made one hundred new bias frames with atikccd-1.15-i386.deb on my Arch laptop and find the horizontal line in mean bias frames, and mean darks independent of exposure time. The line is completely removed with bias subtraction.
The horizontal line was absend in 1.3.
Who done it? :-)
cherno
Last edit: 7 years 7 months ago by Gebhard.
7 years 7 months ago #14241
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Replied by Peter Polakovic on topic Strange Bias on Atik460EX

Strange, there is 8MB buffer again and I can't find any tracks that it was bigger in 1.3... Nevertheless, I increased it to 24MB, can you try version 1.16? Peter
The following user(s) said Thank You: Gebhard
7 years 7 months ago #14256

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Replied by Gebhard on topic Strange Bias on Atik460EX

The horizontal line is gone.
Thank you!

cherno
7 years 7 months ago #14259

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Replied by Stephen Wong on topic Strange Bias on Atik460EX

I tried 1.16 and the download problem came back... EKOS just keep "Downloading...." and does not move after the capture is done on the 1st frame
7 years 7 months ago #14260

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