Saturday, January 4, 2014

Legacy Series, Another Kind of HDR Photography


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.

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