×

INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Automatic ADU bug ?/DarkFlat - Flat counter bug

  • Posts: 207
  • Thank you received: 14
Hi I'm  flats using the auto ADU in the calibration section of the CCD TAB of EKOS. This works most of the time but sometimes if the initial 1 or 2 test exposures are
too great then the algorithm goes wrong. The other day I left the room to make coffee and when I came back it was trying to use 3600 second exposures to get a flat
for my Green filter.
This looks like a 16bit overflow error - eg 2^16+1 is same as 1 in 16 bits, so totally overexposed results in method increasing the exposure.
To correct this I have to stop the exposures and reduce the light source or reduce the initial exposure value, then it works.
2 years 2 months ago #79313

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

Replied by Jasem Mutlaq on topic Automatic ADU bug ?

Thank you for the report. I've added a safe guard against this for next release.
The following user(s) said Thank You: Jim
2 years 2 months ago #79330

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

  • Posts: 401
  • Thank you received: 41

Replied by Euripides on topic Automatic ADU bug ?

Hello Nick,

Could you please tell me in which auto option you are referring? You mean the value we put for ADU ?

I'm trying to optimize my flats.

Hello Nick,

Could you please tell me in which auto option you are referring? You mean the value we put for ADU?

I'm trying to optimize my flats and trying to understand if I am missing something.

Thanks!


  
2 years 2 months ago #79557
Attachments:

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

  • Posts: 207
  • Thank you received: 14

Replied by Nick Birkett on topic Automatic ADU bug ?

Hi Euripides, yes that's correct. When creating a set of Flat jobs in the Camera tab, click on "Calibration". In the flat duration use the ADU and set the desired ADU (I use 25000). Then set the exposures for each flat to 1sec and take the flats. It will take a series of test exposures until it gets
the correct one (according to your ADU) and then it commences taking the Flats at this new exposure. Note once all the exposures have been
been done the exact exposure time can then be seen in the Exposure box. If you want to then create DarkFlat just double click on each sequence
and change "Light" to "Dark" and click the tick box in sequence queue. You will then have a Dark sequence using the exact same exposure as the light.
This is useful if you have a set of filters to go through.
The following user(s) said Thank You: Euripides
2 years 2 months ago #79559

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

  • Posts: 207
  • Thank you received: 14

Replied by Nick Birkett on topic Automatic ADU bug ?

I meant change "Flat" to "Dark" !!
2 years 2 months ago #79560

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

  • Posts: 401
  • Thank you received: 41

Replied by Euripides on topic Automatic ADU bug ?

Ok I think I got it. One last question if you don't mind : "Desired ADU". How do you end up with that value?

My camera is 14 bit so my true ADU is 16000. 

Thanks!
2 years 2 months ago #79563

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

  • Posts: 207
  • Thank you received: 14

Replied by Nick Birkett on topic Automatic ADU bug ?

Ekos scales the ADUs to 16bits , so works same for all cameras. Indi "ADU" is not the one the manufacturer gives.
2 years 2 months ago #79564

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

  • Posts: 207
  • Thank you received: 14

Replied by Nick Birkett on topic Automatic ADU bug ?

Check out the "Bits per Pixel" value in your FITS header. Mine shows 16bits - QHY294M and ASI294MC even though both are "14bit" cameras.
2 years 2 months ago #79565

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

  • Posts: 401
  • Thank you received: 41

Replied by Euripides on topic Automatic ADU bug ?

I bet that mine will be 16bit too, cause as far as I can see those values are "stretched" to 16bit.

The point is how we proceed with that? Do we go with the max value for 16 bit? The max value for 14 bit (the actual true value)? Do we have to put the 30%, 50% of the max value in that field?
2 years 2 months ago #79566

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

  • Posts: 207
  • Thank you received: 14

Replied by Nick Birkett on topic Automatic ADU bug ?

Yes just proceed as if you have a 16 bit camera. It is just a constant scaling so the ADU setting can be the same for any camera (12, 14, 16 bit) all
treated the same by indi.
I use 25000 which is 38% of 2^16 . I think 25-50% is often quoted.
If you run your mouse over an image in FITS viewer, in the bottom right corner you will also see the coordinate (pixels) and value (0-2^16-1).
Also in FITS viewer click the "Statistics" button (3 bars looks like a histogram) and it will show you min, max, mean and median values of the image.
The following user(s) said Thank You: Euripides
2 years 2 months ago #79567

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

  • Posts: 207
  • Thank you received: 14
Hi Jasem. Just tested the new DarkFlat feature. I like it. Take the flats then press "Generate DakrFlats" button to get a new set of jobs.
Ok there is bug. When I take the flats it doesn't update the frame counter so I just end up with 1 Flat for each filter. DarKflats ae fine.
Great work.
2 years 2 months ago #79673

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

I can't replicate the flats issue. If I specify 5 flats, I end up with 5 as usual.
2 years 2 months ago #79674

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

Time to create page: 0.740 seconds