The Helix Nebula, also known as The Helix, NGC 7293, is a large planetary nebula (PN) located in the constellation Aquarius. Discovered by Karl Ludwig Harding, probably before 1824, this object is one of the closest to the Earth of all the bright planetary nebulae. The estimated distance is about 215 parsecs (700 light-years). It is similar in appearance to the Cat's Eye Nebula and the Ring Nebula, whose size, age, and physical characteristics are similar to the Dumbbell Nebula, varying only in its relative proximity and the appearance from the equatorial viewing angle. The Helix Nebula has sometimes been referred to as the "Eye of God" in pop culture, as well as the "Eye of Sauron". --Wiki

I struggled with this one, wanting to show the numerous background galaxies in the area that are visible only with broadband filters, and using narrowband filters to try to see as much detail as possible in this structure. As an aside, I think that maybe broadband would be all that was needed here. But anyway, PixInsight's Pixel Math came to the rescue here.

I think I tried about 100 different combinations on this one, but finally came up with something that was I felt was a good compromise between the details of narrowband and the broadband filters to show the galaxies. Dont ask me to try to remember exactly what it was as I've since deleted the files, but the Pixel Math expression something like this....

R/K: 0.6*Ha + 0.4*Lum

G: 0.4*OIII + 0.3*Ha + 0.3*Lum

B: 0.7*OIII + 0.3*Lum

After coming up with an image from this expression I then worked on blending in the RGB. It was a balancing act for sure, but I hope I've come close to showing a good representation of this area of the sky. Please check out the annotated version that has most of the galaxies labeled. There's one galaxy that can be seen through the Helix that was not labeled. Of course none of these galaxies showed up with the narrowband data, so it was a struggle to find a happy medium.