×
INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

Strange Bias on Atik460EX

4 years 1 month ago
cherno
Junior Boarder
Junior Boarder
Posts: 30
More
Topic Author
Strange Bias on Atik460EX #9028
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
Attachments:

Please Log in or Create an account to join the conversation.

4 years 1 month ago
polakovic
Platinum Boarder
Platinum Boarder
Posts: 712
Karma: 14
More
Strange Bias on Atik460EX #9030
Hi Cherno, in general, you should trust that one which really fits your images. If it is not the same computer, it need not be necessary the same, it may be sensitive to USB port powering or some subtle timing issues.

What operating system and what INDI client do you use?
Can you try to make capture with atik_ccd_test to make sure it is ATIK SDK issue?

atik_ccd_test -short 0.01

It will create short.fits file, try to check, if the lines are also visible.

Peter

Please Log in or Create an account to join the conversation.

4 years 1 month ago
cherno
Junior Boarder
Junior Boarder
Posts: 30
More
Topic Author
Strange Bias on Atik460EX #9042
Thanks for your very fast answer.

polakovic wrote: What operating system and what INDI client do you use?

Operating system is Arch linux. I control the ccds via indi_setprop in a little python script.

Can you try to make capture with atik_ccd_test to make sure it is ATIK SDK issue?

atik_ccd_test -short 0.01

The lines are visible.
Now I looked at the files with varoius zoom levels and found that the indi frames have an additional horizontal line at y=1527 (first pixel is 1/1).

I compared mean biases from two ccds: 460 and 420 and computed the ratio of the means captured with artemis and with indi.
The results are
Indi420/Artemis420: mean=1.000124, min=0.974, max=1.026, sigma=0.00533
Indi460/Artemis460: mean=1.000201, min=0.682, max=1.188, sigma=0.01267

Three laptos were involved: Indi420 and Indi460 on an 9 year old Dell Inspiron, Artemis460 on a Lenovo X220 runnig win7. I don't know which laptop was used to make Artemis420, runnig XP.

Summary: Indi produces a horizontal line on 460, vertical lines coincide in both softwares. Biases from 420 are identical.

I will continue with flats to see if there are issues at higher ADU values.

cherno

Please Log in or Create an account to join the conversation.

4 years 1 month ago
polakovic
Platinum Boarder
Platinum Boarder
Posts: 712
Karma: 14
More
Strange Bias on Atik460EX #9048
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

Please Log in or Create an account to join the conversation.

4 years 1 month ago
cherno
Junior Boarder
Junior Boarder
Posts: 30
More
Topic Author
Strange Bias on Atik460EX #9049
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

Please Log in or Create an account to join the conversation.

4 years 1 month ago
polakovic
Platinum Boarder
Platinum Boarder
Posts: 712
Karma: 14
More
Strange Bias on Atik460EX #9052
OK, I'll make new build tonight. Peter

Please Log in or Create an account to join the conversation.

4 years 1 month ago
polakovic
Platinum Boarder
Platinum Boarder
Posts: 712
Karma: 14
More

Please Log in or Create an account to join the conversation.

4 years 1 month ago
cherno
Junior Boarder
Junior Boarder
Posts: 30
More
Topic Author
Strange Bias on Atik460EX #9077
Perfect!
The horizontal line is gone.

You've done a great job.
Thank you very much!
cherno

Please Log in or Create an account to join the conversation.

3 years 6 months ago 3 years 6 months ago by cherno.
cherno
Junior Boarder
Junior Boarder
Posts: 30
More
Topic Author
Strange Bias on Atik460EX #14241
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
Attachments:

Please Log in or Create an account to join the conversation.

3 years 6 months ago
polakovic
Platinum Boarder
Platinum Boarder
Posts: 712
Karma: 14
More
Strange Bias on Atik460EX #14256
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 cherno

Please Log in or Create an account to join the conversation.

3 years 6 months ago
cherno
Junior Boarder
Junior Boarder
Posts: 30
More
Topic Author
Strange Bias on Atik460EX #14259
The horizontal line is gone.
Thank you!

cherno

Please Log in or Create an account to join the conversation.

3 years 6 months ago
sywong2000
Senior Boarder
Senior Boarder
Posts: 57
More
Strange Bias on Atik460EX #14260
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

Please Log in or Create an account to join the conversation.

Time to create page: 0.711 seconds