My First Attempt at the Lagoon Nebula: A Journey Through Stacking and Light Pollution

Astrophotography. The words themselves conjure images of breathtaking nebulae, distant galaxies, and the silent dance of celestial bodies. For the uninitiated, however, the journey to capturing these wonders is often paved with steep learning curves, frustrating software, and the ever-present challenge of light pollution. My recent foray into stacking images for the first time to capture the Lagoon Nebula was no exception.

The Setup: A Humble Beginning

My equipment for this adventure was a Sony a74 camera with a 135mm GM lens. To maximize reach, I employed the camera's APS-C mode, effectively giving me a 202.5mm focal length. No telescope was involved; just a sturdy photo tripod, manual focus on a bright star, and the trusty Sky Guide app on my phone to point me in the right direction. I managed 80 exposures of 2 seconds each, totaling 160 seconds of light capture, supplemented by 10 dark frames. The skies, unfortunately, were a Bortle 6, a testament to urban light pollution.

The Processing Puzzle

This is where the real beast emerged: post-processing. My first encounter with SIRIL, a stacking and processing software for Mac, was... enlightening, in a challenging way. Tutorials, often tailored for Windows users, presented settings that were mysteriously greyed out on my end, making it difficult to follow along. The aspiration to remove stars using Starnet++, a common step for nebulae imaging, also hit a snag. The installation process required delving into coding permissions, a hurdle I, like many beginners, found daunting.

Despite these challenges, I managed to get through the stacking script, a rudimentary background extraction, and some green tint removal. Color calibration proved to be another obstacle; the software couldn't reliably find stars to perform automatic calibration, and manual adjustments felt like guesswork. Ultimately, I exported the result as a TIFF after performing manual color and histogram stretching, with the stars still present due to the Starnet++ issue.

The Result: A Glimpse of the Lagoon

Here's the image, the culmination of my first real attempt at deep-sky stacking:

Lagoon Nebula

Reflections and Future Steps

Looking at the image, I can't help but feel a mix of accomplishment and a healthy dose of self-critique. The nebula appears smaller than I'd hoped, leading to questions about whether my 202.5mm effective focal length was truly maximizing the frame. Community feedback suggests the image does indeed contain the Lagoon Nebula, along with the Trifid Nebula – a reassuring sign!

One comment pointed out potential "lines" and suggested recentering the target during longer capture sequences to ensure consistent framing. This is a valuable lesson; I had assumed the stacking software would handle all alignment. The advice to use all calibration frames (darks, flats, bias) was also noted, highlighting the importance of a complete calibration workflow.

To those just starting, I echo the sentiment that it's a learning process. Trying simpler tutorials first, like the basic SIRIL guide, seems like a wise approach to avoid being overwhelmed. The question of whether to upgrade to a telescope versus longer lenses for closer-up views is also a common one. As one experienced astrophotographer mentioned, a good telescope is essentially a long lens, but optical corrections can differ. For nebulae, a focal length in the 300-600mm range with an astro camera seems to be a sweet spot for many.

This first attempt has been a humbling but incredibly educational experience. The journey into astrophotography is clearly one of patience, persistence, and continuous learning. I'm excited to refine my techniques, tackle more challenging processing steps, and hopefully bring you clearer views of the cosmos in the future.