Elephant Trunk Nebula / IC 1396

Amadeus21 wrote:

Hello Mark, I'm from Germany and my English is a little rusty. Therefore I may not understand all the details of your text – and your technical setup of that gorgeous picture: How can one expose a single shot of a digital camera over 2,5 hours? And at what optics did you attach the Sigma FP in order to get a picture which reminds me at the $ 3 billion Hubble? If I understand it right, you've taken 3 shots monochrome with 3 different wavelenght filters, colourd each "color separartion" and combined it to one single "pseudo-color picture"? Really fascinating ... I am impressed.

Best wishes
Johannes

Hi Johannes, Thank you! here the answer in English but since I also live and work in Germany If you want I can send you the answer also in German. The total time of around 2,5 hrs is made of individual 5 minute exposures (the longest time a SIGMA fp can expose in Bulb Mode (using a Pluto Trigger). The SIGMA fp is attached to a Celestron RASA 11" via a RAF Camera L-Mount to M65 to M48 combination which attaches to a Baader UFC Filter housing. Baader H-alpha (20 shots) and S-II (10 shots) narrowband filters were used to collect monochrome images. The colour for the stars was taken from a SIGMA fp L full colour image. A few 5 minute exposures with the camera blanked off were used to create a dark file (residual camera background noise) and a "bad pixel map" (to capture as many hot pixels as i can) both of which are subtracted from each of the individual monochrome shots from the fp. The combined S-II shots were pasted into the green and red channels of a blank colour image (several versions with several mixings to give Red/Orange/Yellow) and the H-alpha into a the blue and green channels of a separate blank colour image.  The resulting 3-channel colour images are combined and mixed  in yet a new blank image ... I hope this helps, all the best, Mark