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
- Typical Imaging Sequences Deep Space Objects brighter than 10th magnitude
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