Resolved ST-8XME bias level change

Discussion in 'Legacy Models - Community Support' started by EricG, Mar 29, 2020.

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  1. EricG

    EricG Standard User

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    I recently set up my observatory for the season (I put everything away for the winter as it gets too cold in this part of Canada). I noticed the bias level for my ST-8XME has changed since last fall from approximately 100 to 900 for the main CCD and 13000 for the guider CCD. Otherwise, the camera appears to function normally.

    Any idea what the cause may be? Is it possible it may be caused by software, or is it likely a hardware failure within the camera?

    Thank you

    Eric
     
  2. Doug

    Doug Staff Member

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    We made a change to the default settings for SBIGUDrv. There is a completely unnecessary "Auto bias level correction" feature, which sometimes causes problems with various control programs. So we now default it off.

    You can turn it back on in the SBIG Driver Checker, under Config Drv, but we recommend that you leave it turned off.
     
  3. EricG

    EricG Standard User

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    Thank you for the quick response. I will try turning off the Auto bias level correction. The camera has worked flawlessly for the past 8 years, so hopefully that solves the problem.

    Eric
     
  4. Doug

    Doug Staff Member

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    To be clear: the "problem" is that it is turned off. However, I'm also saying that it's not actually a problem; we recommend that you leave it turned off and accept the higher bias level. That is the camera's actual bias level.
     
  5. EricG

    EricG Standard User

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    Sorry, I misunderstood what the auto corection does.

    I then have questions on the impact on my darks library. How much variability can I expect in the bias level over time? Will I need to update my darks library frequently to account for bias changes? How often should I check the bias level?

    Thank you

    Eric
     
  6. Doug

    Doug Staff Member

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    The bias level should be pretty stable. We haven't had any reports of problems with calibration caused by turning this feature off.

    Of course if you choose to do so, you can turn it back on via SBIG Driver Checker.
     
  7. EricG

    EricG Standard User

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    Perfect. Thank you.

    Eric
     

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