On Monday, March 24, 2014 12:12:38 AM UTC+8, Mikko OH2HVJ wrote:   
   > sgpopticsguru@gmail.com writes:   
   >   
   > >> This is removed in astronomy by taking 'bias images' in dark with   
   >   
   > >> zero exposure time and substracting this from the image.   
   >   
   >   
   >   
   > > Mikko, I do this. If you look at my description, I first measure FPN   
   >   
   > > and take it out. Despite this I see a DC offset later which makes me   
   wonder.   
   >   
   >   
   >   
   > Ok, I was unfamiliar with the FPN term. Do you have a physical shutter   
   >   
   > and what kind of sensor are you characterizing ?   
   >   
   >   
   >   
   > If the strange DC level changes with light level and you do not   
   >   
   > have a physical shutter, could this be optical/electrical leakage   
   >   
   > on the sensor ?   
   >   
   >   
   >   
   > --   
   >   
   > Mikko OH2HVJ   
      
   Mikko, this is a global shutter camera. FPN refers to Fixed Pattern noise. You   
   can google it.   
      
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