The Orion Nebula, as you've never seen it before!
I've had the pleasure of testing a new filter from Antlia -- the Antlia ALP-T Dual-Band SII & Hb! This is a dual-narrowband filter with 5 nm bandpasses around the sulfur-II and hydrogen-beta lines (deep red 672 nm and blue 486 nm, respectively).
H-beta, being of a shorter wavelength, means that the state of hydrogen gas that must be excited to emit this light is higher than H-alpha, so it doesn't always exist in the same places as H-alpha. Although, anyplace there is H-beta, there will be H-alpha signal as well, and it will be stronger. Not as many nebulae emit H-beta, but I intend to hunt some down...I recently bought a dedicated H-beta filter from Farpoint's recent moving sale, which I'm excited to mess around with as well in monochrome.
The H-beta signal in this image was quite a bit brighter than the SII, but I split the RGB channels, bumped up the red, and re-combined them, which worked great. (Just selecting red using a ColorMask filter wasn't getting very much of it.) I had to stretch and do curves adjustments verrrrrry carefully to not blow out the core, and then HDRMultiscaleTransform came in and took care of the rest.
Visually looking through the filter shows a beautiful deep turquoise and a red-purple, so I have tried to replicate that here.
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