Contents - Index

Dark & Bias Frames

CCDAutoPilot give many possibilities for automatically acquiring calibration frames to make maximum use of your available evening.  Without good calibration data, your resultant images will be less than they could be.  Dark and Bias Frames, together with Flat Frames, provide the calibration data needed for best results.  The Utility Window can help you obtain darks in whatever time is available before or after your light frames.



For each series, the checkbox at the left of each series enables or disables that series.  When disabled, the series information is grayed out.  When the Flush Imager series is checked, the series will be run once before any subsequent dark or bias frames are acquired.  The Flush series is used to remove any residual image that may remain after light frame exposures of bright objects.  You should experiment with your specific camera to see what kind of flush series is appropriate. 

The remainder of the settings for each series is:
  • Relative to Light Frames: You have the ability to take the series before, after or both before and after the light frames.  Depending on your automation plan, you can maximize the calibration frames acquired in an evening this way.
  • Number: This is the number of exposures that will be taken in this series before moving on to the next series.
  • Filter: This is the filter that will be used for this series.  Filter naming and selection will be according to the names and capabilities of your camera control program.  If you have a shutterless camera, you can select an opaque filter slot for your darks.
  • Binning: This is the degree of binning that will be used for this series.  Binning will be according to that reported by your camera control program and your specific camera.
  • Type: Select either bias or dark.  A bias frame is essentially a 0-length exposure time dark.
  • Exposure Time: This is the length of time your camera will be exposed in seconds.
  • Description: Here you can enter a specific description for the exposure.  If no description is entered, a default file name for the exposure will be automatically generated.  For a bias frame, the file name will be <Camera temperature>Bias<Binning>_<yymmdd>_<sequence number>.fit, where <Camera Temperature is the operating temperature of the camera, Binning is the selected binning, <<yymmdd> is the date the exposure is taken and <sequence number> is the 5-digit sequence number used to identify one exposure from another.  For a dark frame, the default file name <Camera Temperature>Dark<Exposure Time><Binning>_<sequence number>.fit.  The only difference from the bias frame default is the addition of the exposure time to the file name.  If you enter a description, the file name will be <Description>_<yymmdd>_<sequence number>.fit, where <Description> is the description entered.  Since the description will ultimately be part of the data file names, it must not include the Windows "forbidden characters", '*/:<>?|'.  Such characters will be stripped from the target name if present. 

    Below each item in Series 1 is the button, which replicates the series 1 settings into all of the other series for easy editing
  • Number of Dark Sets: This is the number of times each series will be repeated.  
  • Dark Frames Now: This button will take the dark and bias frames specified on this series immediately.  All that is required is a camera connection.
  • Readout Mode: Sets the readout mode used for dark and bias frames.  See Readout Modes.  This selection is available only with Maxim version 5.


    Utility Window



    The Utility Window shows your planned light frames and, this case, the dark frames that are acquired before and after the light frames.  The sky flat acquisition time is also provided.  In this example, I wait until 21:00 to start so that my first target can get above 45° east altitude.  During the time between civil dusk at 19:48 ant the first target start time, I grab some dark frames to refresh my dark library.  Similarly, I see some time between the last target's light frame and the start of dawn flats so I can grab some more dark frames.  Thus, you can maximize your camera usage during the entire evening if you wish.