Presenting,
Lord of the Rings...
The planetary nebula M57 (Ring Nebula), is located in the constellation Lyra and situated between the stars Beta and Gamma Lyrae. The nebula is formed by the dying stages of a star. When a star’s core fusion diminishes, the forces of gravity take hold changing the star’s structure. Gravity causes the external structure to collapse inwards, causing the internal structure to become condensed and extremely hot. The intense build up of pressure causes the external shell to explode and is forced away. The stellar wind causes the surrounding gases to ionize producing vibrant colours. The Ring Nebula is about 2,000 light-years away and has a diameter of about one light-year.
About this image;
Total exposure time is 1 hour – (R:20;V:20;B:20) using five 240sec subs per channel and is a RRVB composite. I titled this image as wide field as it does include a small vista of stars surrounding the nebula to deliver an aesthetic feel, however in reality it is far from it - the image was captured at a focal length of 3572mm. This is my first attempt at RVB imaging, which I found reasonably challenging. Having performed a G2V colour balance through the photometry filters, it took a while to get the balance right... and guess what?... Its still not right! Conventional RGB weightings are much easier as there is quite a lot of channel “cross-over” with the RVB. After all, they aren't really design for this style of imaging (compared to collecting scientific data). If you’re looking for a challenge, give RVB imaging a try.
Processing;
Other than the troubles mentioned above regarding the colour weightings, after the lights were calibrated they were still riddled with serious noise. That data raw data was rather good coming from an NABG chip - no blooms and the like. I don’t think the scaling of the calibration files worked well.
The image still contained a lot of noise after median combining. I was tempted to chase the remaining problems with the healing tool, but for what its worth I didn’t bother. This is not one of my “front page/top shelf” images. I did this to challenge my skills and do something different than RGB for a change. Other than this, the processing of the image was rather straight forward. I used the R channel as a luminance and pushed it through LR deconvolve – 2 iterations. This was then added to the RVB as a luminance. The luminance was stretched with levels and curves. The RVB with levels and shadow/highlights tool. I used a high-pass layer mask to selectively improve contrast in specific areas of interest.
While I'd normally say "Enjoy", I don't think there is much to enjoy about this image. Perhaps I'm being a little too harsh, but I'm not overly thrilled by this image despite the underlying technical challenges I faced. I thought I'd share it anyway. So to this end... I hope you "partially" enjoy!
, been trying to hunt this down myself from the uk but my light pollution is causing observing havok !!
