Capturing the Cygnus Loop: A Homemade Adapter for E-mount Lenses and Ha Imaging
Astrophotography often presents unique challenges, especially when trying to adapt specialized equipment for new purposes. One such hurdle can be capturing narrowband data – like the vibrant hydrogen-alpha emission – with lenses not originally designed for astronomical modification. This is exactly the challenge faced by our astrophotographer, who aimed to image the magnificent Cygnus Loop without permanently altering their everyday Sony camera.
The Problem: E-mount Lens Limitations
The Sony E-mount, known for its short flange distance, makes it difficult to use standard commercial adapters for astronomical cameras like the ZWO ASI2600MC-Pro. The limited space between the existing ZWO tilt plate and the camera sensor meant there was no room for a filter holder. This presented a significant obstacle for capturing the crucial Hydrogen-alpha light from the Cygnus Loop.
The Solution: A Custom-Fabricated Tilt Plate
Undeterred, the solution involved a bit of ingenuity and hands-on fabrication. A custom tilt plate was created, complete with a built-in Sony E-mount. While not the easiest to swap out, this modification allowed for the necessary infinity focus with the Rokinon 135mm F/2 lens. Since there was no internal space for a filter, the solution was to front-mount the filter on the lens itself, using adapters. This approach, while limiting the lens aperture to roughly F/4 due to the 2" filter size, effectively enabled the capture of the desired H-alpha signal.
The Imaging Rig and Data
Here’s a breakdown of the impressive setup used for this capture:
- Camera: ZWO ASI2600MC-Pro at -10°C
- Lens: E-mount Rokinon 135mm F/2 (with custom E-mount tilt plate)
- Filter: Antlia ALP-T 5nm Ha+Oiii
- Exposure: 4 hours 45 minutes (95 x 3-minute subs)
- Mount: EQ6-R Pro
- Guiding: Svbony 60mm F/4 doublet with ASI120MM
- Acquisition Software: KStars/EKOS/INDI on an N100 mini PC
- Processing Software: Siril/GraXpert/StarNet/Pixinsight
- Location: Bortle 8 skies
The Result: The Majestic Cygnus Loop
The hard work and innovative approach have paid off beautifully, resulting in a stunning image of the Cygnus Loop – a supernova remnant located about 5,000 light-years away in the constellation Cygnus. This intricate celestial structure, with its wisps of gas and dust, is a testament to the violent death of a massive star.
This project not only showcases the beauty of the Cygnus Loop but also highlights the power of creative problem-solving in astrophotography. By adapting existing equipment and pushing the boundaries of what's possible, stunning results can be achieved even in challenging conditions.
