47-10 Bias Frames

Discussion in 'Aluma CCD Series' started by mike m benjamin, Jan 24, 2023.

  1. mike m benjamin

    mike m benjamin Cyanogen Customer

    Joined:
    Jul 20, 2018
    Messages:
    155
    I am just starting to use my new 47-10 Aluma and and going through taking Bais and Dark frames. I have only used Kodak and Sony chip cameras in the past, the bais frame looks completely different to what I am used to seeing as far as pattern noise. Do these look normal?

    Mike Benjamin
     

    Attached Files:

  2. Colin Haig

    Colin Haig Staff Member

    Joined:
    Oct 27, 2014
    Messages:
    6,567
    Location:
    Earth
    Yes, the Teledyne e2v sensors look completely different than the ON Semi (Kodak) and Sony devices. Keep in mind they have huge well depth, and different location for read amplifiers and logic.
    I'll ask @Doug to take a look at the "Baismaster" that you produced with PixInsight. I see about 10 ADU total variation in the PI averaged image. It looks reasonable to me, but @Doug is the expert.
    Can you give us a bit of detail on how you created that Bias master?
    e.g. number of bias frames used, how did you combine them, which averaging/weighting etc?
    PixInsight is notorious for making it easy to trash or misinterpret the science data; we can't interpret the process used from the history.
     
  3. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    9,397
    I always find it hard to interpret anything processed by PixInsight, because it changes the dynamic range from 0-65535 to 0-1, and I don't know how that scaling was actually applied. So it's hard to get anything quantitative out of that.

    More to the point, if you create two master bias frames from different raw frames using the same process, does any residual pattern subtract out?
     
  4. mike m benjamin

    mike m benjamin Cyanogen Customer

    Joined:
    Jul 20, 2018
    Messages:
    155
    Hi Colin/Doug,

    80 frames, combination- average
    Weights- PSF signal weight
    ImageIntegration

    Doug, using Maxlm DL I combined the 80 frames to create a master, and tonight another 80 to make two masters and using your pixel math subtracted the two and there is no residaul pattern. So I suspect all is fine.
     

    Attached Files:

  5. Colin Haig

    Colin Haig Staff Member

    Joined:
    Oct 27, 2014
    Messages:
    6,567
    Location:
    Earth
    Mike, I suspect the weighting is part of the problem. There is no "point spread function" to a bias frame - PSFs apply to stars.
     
    mike m benjamin likes this.

Share This Page