Saturday, January 4, 2014

Legacy Series, Another Kind of HDR Photography

M42


Finally, some time and sky to work on long exposure webcam-astronomy... The remaining clouds allowed an open view on Orion. M42, certainly one of the more prominent objects, easy to see and easy to record, gives a perfect light source for experimenting as it includes a very bright open cluster as well as a dark cloud and a bright nebula.


Instrument
ETX-70 equatorial mode, #494 autostar
Camera
ToUCam pro PCVC-740, Baader IR filter
Data acquisition K3CCDTools, 10s exposures
Data registration
RegiStax 2, K3CCDTools
Frame stacking
RegiStax 2, K3CCDTools
Postprocessing
RegiStax 2 & IrfanView, iMerge

Some resulting images (based on the same recorded AVI file - have a look at a compressed WMV version) were obtained using different sets of postprocessing parameters (contrast, brightness, saturation, gamma curve, etc.) in order to respect the different aspects of the complex object. All image tuning steps were carried out on all pixels equally (no area selective tinkering).



The Results



Image resulting from registration and stacking, no postprocessing



The above "raw" image postprocessed using IrfanView



Light postprocessing using RegiStax


Massive fiddeling with RegiStax and IrfanView postprocessing


Registration using K3CCDtools linear scale


Registration using K3CCDtools logarithmic scale


All above combined using iMerge


The Observatory

Have a look at my hyper-professional setup to catch the hole in the clouds (greyish stuff above the roofs in the background). Even though the mechanical setup looks pretty solid, the RA motor of the fork produces some jitter occasionally. Consequently I performed a manual selection of the frames to be registered, resulting in a loss of about 30% of the 10sec frames.


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