Deep Space Imaging Techniques

Equipment

  • Scope – 18 inch (450 mm) f/4.5 Newtonian Reflector
  • Camera:  SBIG STL-11000M class 2
  • ASA 3 inch zero power coma corrector
  • An AWR drive corrector
    • An inverter and quartz oscillator for synchronous motors
  • MacBook Pro compputer running Windows 10 in native mode
  • Two marine batteries
    • 1 for the camera – the camera is a power hog!
    • 1 for everything else
  • Robofocuser to remotely control focus
  • Maxim DL software for controlling the camera, drive corrector, and collecting the images

Imaging at the Telescope

  • Imaging Techniques
    • Typical Imaging Sequences Deep Space Objects brighter than 10th magnitude
      • For most deep sky objects, I typically use 3 minute exposures for brighter objects
      • When I’ve used longer exposures, I tend to “blow out” the bright sections of the object  Notably galaxies and compact globular clusters
      • Blow out meaning the bright area are fully saturated at 65k white  This mean you lose the ability to see details in these regions
    • Exposures are 3 minutes for
      • Red, blue, and green 2×2 pixels
      • Luminance 1×1 pixels
    • Objects fainter than 10th magnitude, I increase the exposure duration to 5 minutes per filter
    • In all cases, I try for a minimum of 5x images for each color filter and Luminance

Post Image Collection Processing Overview

  • I use Maxim DL to clean up the images
    • Removing the pedestal
    • Bias
    • Flattening
    • Hot and cold pixel removal
    • Aligning all images
    • Creating the RGB color image
  • Once all that is done, I use Adobe Photoshop and PhotoNinja for additional processing
    • In Photoshop, I process the Luminance and RGB color layers separately
    • When I think I’ve got them optimized, then I merge the layers and apply the Luminosity layering filter
    • Then merge the composite into a 16 bit TIFF file
  • Next, I use PhotoNinja to clean up noise, adjust the blackness of the images and tweak the detail
    • PhotoNinja has probably one of the best noise smoothing algorithms
    • Once all that is done, I prouodly share my images to the world!!
  • There are many more steps, but these are the general steps I use to get an image
  • Typically, I will spend 8-20 hours processing one image