Andromeda Unveiled: A Journey from City Lights to Nebulosity

Moving from the oppressive glow of a Bortle 9 city to the darker skies of Orono, Maine, has been a revelation for my astrophotography journey. Even at Bortle 5, the difference is astounding, and for the first time, I was able to capture the subtle nebulosity of the Andromeda Galaxy (M31) without my image being completely blown out.

This image represents a significant step forward, showcasing the detailed structure of our galactic neighbor. I'm eager for any feedback you might have!

The Gear and the Process

Here's a breakdown of the equipment and settings used to capture this view of Andromeda:

• Mount: Star Adventurer GTI
• Camera: Nikon Z5
• Lens: Tamron 70-300mm (zoomed to 300mm for this shot)
• Light Frames: 120 frames at 30 seconds exposure and ISO 500
• Calibration Frames: 20 dark frames at the same settings.

Post-processing involved stretching the data in Siril to bring out the galaxy's details, followed by subtle edits in GIMP to enhance the overall presentation. This is an uncropped view of the final result.

Calibration Frames: Darks, Flats, and Biases

In the comments, a crucial discussion arose regarding calibration frames. For those new to astrophotography, understanding these frames is key to producing clean images:

• Dark Frames: These are essential for reducing thermal noise generated by the camera sensor. They are taken with the lens cap on, using the same exposure time and ISO as your light frames. It's important to take a fresh set of darks each night as sensor temperature can fluctuate.
• Flat Frames: Flats help correct for uneven illumination across the sensor, such as vignetting (darkening of the corners) caused by the lens or dust particles on the sensor or optical train. You generally need to take flats for each different focal length and aperture combination you use, and ideally each time you set up your equipment as dust can shift. A common method is to point your camera at a uniformly illuminated surface (like an evenly lit sky or a light box) and take several shots at the same exposure and ISO.
• Bias Frames: These are the shortest possible exposures (e.g., 0.01 seconds) taken with the lens cap on. They help to correct for the inherent electronic readout noise of the camera sensor.

For more in-depth information on calibration frames, I highly recommend checking out resources like the one mentioned, which provides a brief guide to understanding their purpose and creation:

Clear skies!