Sky-Watcher 12-inch f/4.9 Parabolic Primary Mirror for Dobsonian FlexTube 300P

This 305 mm parabolic primary mirror is the core optical component for a 12-inch Dobsonian telescope, delivering exceptional light grasp and resolution for deep-sky and planetary observation. With a focal length of 1500 mm and a fast f/4.9 ratio, it gathers over 1400 times more light than the naked eye, revealing faint galaxies, nebulae, and intricate lunar and planetary detail.

Advantages

The mirror features a diffraction-limited parabolic figure with a surface accuracy of 1/8 wave PV, ensuring sharp, high-contrast images across the entire field. Its borosilicate glass substrate provides excellent thermal stability, minimizing cool-down time and maintaining figure under changing temperatures. The enhanced aluminum coating with SiO2 overcoat achieves over 94% reflectivity, maximizing light throughput for brighter views. This mirror is a direct replacement or upgrade for Sky-Watcher Dobsonian FlexTube 300P (12-inch) telescopes, offering a straightforward way to restore or improve optical performance.

Suitable for

• Replacing a damaged or degraded primary mirror in a 12-inch FlexTube Dobsonian
• Upgrading to a higher-quality optical surface for demanding visual observation
• Astrophotography projects requiring a fast f/4.9 parabolic mirror
• DIY telescope builders seeking a premium 305 mm mirror

Key specifications

• Mirror diameter: 305 mm (12 inches)
• Focal length: 1500 mm
• Focal ratio: f/4.9
• Mirror type: Parabolic primary mirror
• Optical material: Borosilicate glass
• Coating: Enhanced aluminum with SiO2 protection
• Reflectivity: >94%
• Surface accuracy: 1/8 wave PV
• Mirror thickness: approx. 38 mm
• Light gathering power: 1440x human eye
• Mounting: Unmounted (mirror only)

Recommendations

For optimal performance, ensure the mirror is properly collimated and protected from dust and moisture when not in use. Consider a high-quality mirror cell and cooling fan to reduce thermal currents.