M20 is among the most commonly imaged objects of the summer sky so there's no need to introduce this object!  Like everyone else I'm drawn to image the Trifid because of it's beautiful colors and fascinating detail.  In fact, it's the only object that I've imaged with every single imaging system that I've owned...and there it was rising late at night while I set up my new refractor in Chile.  So, I caved in to give it one more try but this time with a slightly different goal in mind.  I wanted to use enough exposure to clearly reveal the complex background dust and gas that surrounds the nebula.

The challenge for me lies in the processing.  I'm finding that processing wide field data to be quite different than processing galaxy data from my bigger systems.  This image shows the Trifid floating in a sea of orange/brown dust with the reddish glow of Ha regions glowing in the background.  In this case,  interstellar dust will scatter out the blue component of the background Ha emissions shifting its color from magenta toward a red-ish hue.  Other dusty regions will appear more brown-sh and will filter the color from distant stars in the Milky Way to appear more yellow/orange.   I used SPCC to calibrate the colors so I believe that the colors are in the right ballpark.  The glowing Ha regions of the nebula show the normal bright magenta color produced by the combination of the bright deep-red Ha-alpha spectral line with the fainter deep-blue Ha-beta spectral line along with the blue parts of the nebula caused by the light reflecting from a nearby blue (i.e. hot) star.  The combination of both an emission nebula and a reflection nebula are a big part of what makes the Triffid so beautiful.

The challenge that I had with this image is more artistic and it involved trying to balance the background colors and detail so that it doesn't overwhelm the main subject.  I messed with this 20 different ways with multiple crops and other color/sharpening tricks to add some depth but frankly, I just couldn't satisfy my idealized notion of how the Trifid should appear to float above the background.  So, I finally abandoned my effort to somehow pull a magic trick to create more depth.  In the end, I slightly reduced the impact of the background using masked MorphologicalTransform and accepted that this is pretty much how this region of the sky looks.  This image shows about half of the full frame and I've cropped it to nicely show both M20 and M21.

As always C&C is welcome so feel free to let me know how it works on your monitor.

John