Orion 200mm
Atik 383L+
29x 600s
13x 900s Oiii, 1x1
I use a modified HOO palette. I like the fact that HOO is similar to natural colour, but I find the pure version too stark. I use PixelMath to blend the colours.
Very cool! I will have to try this in my next processing session Thank you for sharing Kathy!KathyNS wrote: ↑Tue Sep 28, 2021 11:58 amI use a modified HOO palette. I like the fact that HOO is similar to natural colour, but I find the pure version too stark. I use PixelMath to blend the colours.
red = 1.5 *Ha - O3
green = 0.4 *Ha + 0.325 * O3
blue = O3
The red formula is very unconventional: that minus sign is not a typo. Even with much longer exposures, my Oiii signal tends to be weak and buried in the noise for most nebulae. Subtracting it from theHa signal prevents the latter from overpowering the Oiii. But, since I am thereby reducing theHa , I have to amplify it with the 1.5 factor. I run the risk of saturating theHa signal, but it hasn't happened yet.
The blending ofHa and Oiii in the green channel is what produces the post-apocalyptic oranges that I like. I suppose that, since there is moreHa than Oiii in the green, I should call it modified HHO. But I think the results are closer to the red-blue of HOO than to the yellow-blue of HHO.
I only use these formulae on starless images. I process the stars separately, using straight HOO, to avoid saturating them. Or else, I replace them withRGB stars, if I have them.
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