Sky Flats

Discussion in 'Aluma AC Series CMOS' started by Sreilly, May 4, 2024.

  1. Sreilly

    Sreilly Cyanogen Customer

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    What is a good target value for sky flats with this camera? What I recall going for with the STL/STX was like 30,000 ADU.
     
  2. Colin Haig

    Colin Haig Staff Member

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    AC4040BSI. Try about 15-30%. eg 4095 is saturation in 12-bit High gain mode, so you want to be maybe around 1000 to start.
     
  3. Sreilly

    Sreilly Cyanogen Customer

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    Thanks Colin. So I'll set the ADU limit to 1000 and give it a 300 ADU target tolerance. What would you suggest for minimum exposure? I currently have it set to .1 second. This is being setup in ACP Scheduler via script for Dusk/Dawn flats.

    AutoFlatConfig.JPG
     
  4. Colin Haig

    Colin Haig Staff Member

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    I have no way to estimate it - too many variables with the largest scope, high QE, and unknown sky conditions.
    You could always try 0.01 and see what ACP typically shoots at.
    Keep in mind the shutter is electronic; the mechanical shutter is only for shooting darks; so the camera can do very short exposures.
     
  5. Sreilly

    Sreilly Cyanogen Customer

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    Good point, I'll change that now. What about the tolerance? Thanks
     
  6. Colin Haig

    Colin Haig Staff Member

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    You're going to need to experiment; I can't offer guidance as it is specific to your setup.
     
  7. Sreilly

    Sreilly Cyanogen Customer

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    OK, flats appear to be underway but how do you set gain via the flat plan? This is using ACO Scheduler to do Dusk/Dawn flats. It started as expected but was automatically set to HDR (default?) If I'm shooting via High Gain wouldn't the flats need to be High Gain as well? I guess I also need to know how to set gain for the Scheduler planned images as well. Is there a setting in MaxIm for default gain setting?
     
  8. Colin Haig

    Colin Haig Staff Member

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    I think that's a question for @Bob Denny - the camera readout mode selected which gain mode (high,low,hdr,StackPro).
     
  9. Sreilly

    Sreilly Cyanogen Customer

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    I've posted in ACP forum but was wondering because every time I open and connect in MaxIm it seems to default to HDR mode instead of last used mode which I would have expected.
     
  10. Colin Haig

    Colin Haig Staff Member

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    That's interesting. Let me see if I can reproduce that behaviour here.
     
  11. Sreilly

    Sreilly Cyanogen Customer

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    So I was able to take sky flats the other evening and again, even with the camera connected and set at High Gain, when the flats started via ACP Scheduler, the setting immediately went to HDR and started taking test shots for sky brightness. When I stopped the run and set to High Gain it stayed at High Gain and took the Flats. And I was incorrect in the statement that every time I would restart MaxIm it would default to HDR, it actually was still at High Gain until it started to take the flats or for that matter any frames, it then went to HDR.
     
  12. Sreilly

    Sreilly Cyanogen Customer

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    Anyone you know of using the AC4040 or I guess any SBIG CMOS cameras assuming they all have the same gain configurations in MaxIm? Any idea how to script this so it goes to a specific gain setting via a plan? If not that makes the ability to use it remotely in the setting the owner wants not so favorable.
     
  13. Colin Haig

    Colin Haig Staff Member

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    ACP has a facility to set the Readout Mode.
    There's a file for defining the readout modes that you want (RoModeInfo.txt), and there are directives (commands) available for script/schedule to set the modes eg #romode or #readoutmode
    This has been around for a while, not just for the AC4040, but for cameras that have fast readout modes useful for pointing correction images or focusing, vs slow readout modes useful for highest quality images.

    Again, please contact @Bob Denny at DC3Dreams.
     
  14. Sreilly

    Sreilly Cyanogen Customer

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    Colin I had hoped to do some further testing last night but had very sporadic connection to the system. Seems the solar events are having an affect on the communications/system as it was sporadic at best. I was able to shutdown the system and call it a night. And yes, I saw the reply on the ACP forum and have setup the file with all entries as High Gain so hopefully that will be resolved for now.
     

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