The Soap Bubble Nebula (PN G75.5+1.7) is an exceptionally faint planetary nebula. Because of its extremely low surface brightness, detection improves significantly with increased aperture—more photons mean more detail in the faintest structures. In this context, a 152mm apochromatic refractor will naturally outperform a 106mm refractor like my FSQ-106, especially when using narrowband filters such as [O III], which captures the dominant emission from this nebula.
That said, I’m attaching a comparison of your image with mine, not to critique contrast—since the larger 152mm aperture will naturally show finer structure when zoomed in—but to highlight a few stylistic and processing choices that affect how the nebula appears.
A key factor is how emission lines are mapped to color channels in my image. The Soap Bubble emits almost exclusively in the [O III] line at 500.7 nm, with minimal H-alpha and virtually no [S II] signal. Therefore, color assignment during post-processing has a direct impact on the nebula’s visibility.
Personally, I tend to favor a naturalistic palette when possible, aligning emission wavelengths with their visual spectrum counterparts:
[S II] → Red
H-alpha → Green
[O III] → Blue
From what I see in your version, [O III] appears correctly mapped to blue, but H-alpha and [S II] may both be contributing to the red channel. While this can create a pleasing aesthetic for richer emission regions, it may increase the Soap Bubble’s prominence since its signal is confined almost entirely to [O III] but there is no green hue mapping?
I'm not entirely sure but I do witness, with my color assignement anyway - that when I add in the full spectrum the soap bubble blends more into the background.
Also, I tend to preserve the star field in and around most of my images. While it adds complexity to processing, I feel the stars tell a story—anchoring the scene and providing both scale and context. In my humble opinion, they’re as much a part of the narrative as the nebula itself.
