I stumbled across some old H-alpha data of the Flame Nebula (NGC 2024) that I had forgotten about. The data consisted of 20 x 30sec lights; 20 darks; 50bias; and no flats.
I stacked and processed the data with PixInsight. The data was not as noisy as I expected it to be. Most of the noise was caused by the banding typical of Canon cameras but the Canon Banding Reduction script easily handled it. Processing was more trial and error than a specific direct approach. I admit I was bit sloppy with my technique but I used this opportunity to explore the MMT tool (if you have time, I highly recommend familiarizing yourself with that tool, it's very versatile). I extracted a lum layer and used the masked stretch process to create a non-linear mask and decreased the contrast with curves (output on curves around 26% on the left side and around 56%-57% on the right side) I played around with MMT to smooth out the rest of the noise using linear scaling set to 3 instead of dyadic on a total of 8 layers with the threshold of the first two layer set to 10 and slowly decreasing each subsequent layer, the last two (layers 7 and 8) the threshold was set to 2.
Starnet2 to to remove the stars then inverted the nebula and used SCNR (green) to remove the magenta and then inverted the nebula back, this is what made it look a little more orange. I left the stars the same and combined everything together using pixel math.
a couple of soft passes through Arcsinh stretch.
UnsharpMask using lum layer as a mask. The image was saved as a JPG and opened with Adobe lightroom mobile on my phone for the last pass of noise reduction for both color and lum layers.
When this object comes back around in a couple months I may try to combine it as a lum layer with RGB data.
The 12nm H-alpha filter did a great job keeping the stars small and I am especially pleased at how well it was able to handle Alnitak.
-Lou
Canon EOS Rebel XS (full spectrum mod)
Astronomik 12nm H-alpha Clip-in filter
Orion thin off axis guider
QHY5L-II M guide camera
Celestron CGX,Edge HD 8,0.7x focal reducer
Optec TCF-Leo focuser
