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Re: [ccd-newastro] Re: Translating full well depth to flat ADU's

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  • Michael Miller
    I m sorry I was using my current camera data which has a well depth of 25,000. I trying to plan for my new camera which has a well depth of 30,000. I was
    Message 1 of 9 , Mar 25 10:20 AM
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      I'm sorry I was using my current camera data which has a well depth of 25,000. I trying to plan for my new camera which has a well depth of 30,000. I was trying to figure out if I was doing it correctly with the old camera.

      Michael D Miller
      CEO VP Services


      On Mar 25, 2012, at 10:03 AM, "randy_nulman" <rj.nulman@...> wrote:

      > Your numbers based on 25K full well depth and the numbers quoted below by Ron indicate similar results. I agree with everything Ron stated below. Is your full well depth 25 or 30?...I am pretty sure your gain measurements are correct.
      >
      > Randy Nulman
      > http://nulman.darkhorizons.org
      >
      > --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@...> wrote:
      > >
      > > That report is calling gain 'Conversion Factor'. Gain is electrons per ADU.
      > >
      > > AT 0.45e-/ADU, your saturation point is 66k if your well depth is 30k, or 55k if your well depth is 25k.
      > >
      > > The optimal level for flats depends on the linearity of your detector. If you have an anti-blooming chip, the 40-50% of saturation is a good place to be. If you have a non-antiblooming chip, then you might be able to go as high as 70-80%. You can use a series of images of a dim star to measure linearity of response if you want to push the envelope and use as high a flat level as possible (for best S/N).
      > >
      > > Ron Wodaski
      > >
      > >
      > >
      > > On Mar 25, 2012, at 9:41 AM, Michael Miller wrote:
      > >
      > > > This is the measured data from my current camera from AIP. I guess I still
      > > > don't see gain?
      > > >
      > > >
      > > >
      > > > Characterize CCD Camera
      > > >
      > > > Images used.........
      > > >
      > > > Bias Frame #1: E:\astrophotography\QSI DARKS BIAS\Bias
      > > > Files\2-9-12\Bias -35 2-9-12-009.fit
      > > >
      > > > Bias Frame #2: E:\astrophotography\QSI DARKS BIAS\Bias
      > > > Files\2-9-12\Bias -35 2-9-12-007.fit
      > > >
      > > > Flat Frame #1: E:\astrophotography\Flats by
      > > > date\3-20-12\AutoFlat-Dawn-Green-Bin1-005.fts
      > > >
      > > > Flat Frame #2: E:\astrophotography\Flats by
      > > > date\3-20-12\AutoFlat-Dawn-Green-Bin1-004.fts
      > > >
      > > > Dark Frame: E:\astrophotography\QSI DARKS BIAS\Darks 1800
      > > > 2-5-12\Darks -35 2-6-12 1800-0031800.fit
      > > >
      > > > Measurements........
      > > >
      > > > Bias Sum Mean: 502.476 ADUs
      > > >
      > > > Bias Diff StdDev: 33.2372 ADUs
      > > >
      > > > Flat Sum Mean: 57639.8 ADUs
      > > >
      > > > Flat Diff StdDev: 356.01 ADUs
      > > >
      > > > Dark Frame Mean: 262.976 ADUs
      > > >
      > > > Derived Results.....
      > > >
      > > > Conversion Factor = 0.45 electrons/ADU
      > > >
      > > > Readout Noise = 10.69 electrons RMS
      > > >
      > > > Mean Dark Current = 0.002966 e/pix/sec during 1800.0 second exposure at
      > > > -35.0 C
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > From: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com] On
      > > > Behalf Of randy_nulman
      > > > Sent: Sunday, March 25, 2012 8:07 AM
      > > > To: ccd-newastro@yahoogroups.com
      > > > Subject: [ccd-newastro] Re: Translating full well depth to flat ADU's
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > Hi,
      > > > The full well depth in electrons needs to be converted into ADU values.
      > > >
      > > > You do this by dividing the full well depth by the "gain" as specified for
      > > > your camera...should be close to 65,000 adu units (give or take assuming a
      > > > 16bit camera).
      > > >
      > > > Then, for your flats, a good number is around 40 to 50% of this net value.
      > > >
      > > > Hope this helps,
      > > > Randy Nulman
      > > > http://nulman.darkhorizons.org
      > > >
      > > > --- In ccd-newastro@yahoogroups.com <mailto:ccd-newastro%40yahoogroups.com>
      > > > , "Michael" <circpro@> wrote:
      > > >>
      > > >> I want to make sure my flat exposure is correct with a new camera coming.
      > > > The specs say the full well depth is 30,0000 electrons. How does that
      > > > translate to flat exposure?
      > > >>
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > [Non-text portions of this message have been removed]
      > > >
      > > >
      > > >
      > > > ------------------------------------
      > > >
      > > >
      > > >
      > > >
      > >
      >
      >


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