Sky-Watcher primary mirror 305/1500
Looking for a quality replacement or upgrade for the primary mirror in your Newtonian reflector? The Sky-Watcher primary mirror with 305mm aperture and 1500mm focal length is exactly what you need. This optical component is manufactured directly by Sky-Watcher and meets the strict demands that astronomers place on precision workmanship and light reflection quality. Whether you are repairing an existing telescope or building your own Newtonian from scratch, this mirror provides a reliable foundation for years of observation.
Pyrex substrate - thermal stability for sharper images
The mirror substrate is made from Pyrex - a borosilicate glass that has a significantly lower coefficient of thermal expansion compared to standard soda-lime glass. In practice, this has a fundamental impact on the stability of the optical surface during nighttime sessions. As temperatures drop, a Pyrex mirror retains its shape considerably longer and more accurately than a cheaply produced alternative made from ordinary glass. For both visual and photographic observation, this means a shorter acclimatisation time and a more stable image throughout the entire night.
What a 305mm aperture gives you
A 305mm mirror belongs among the largest optics that are still reasonably portable and accessible for enthusiasts. The light-collecting area of such a mirror is approximately 730 cm², which represents more than double the light collection of a popular 200mm mirror. In practice, this means you will see fainter objects, finer detail in nebulae and galaxies, and significantly better performance when observing globular clusters or planetary nebulae.
The 1500mm focal length and the resulting focal ratio of approximately f/4.9 are very favourable for both wide-field visual observation and deep-sky astrophotography.
| Parameter |
Value |
| Aperture |
305 mm |
| Focal length |
1500 mm |
| Focal ratio |
f/4.9 |
| Light-collecting area |
approx. 730 cm² |
| Substrate material |
Pyrex (borosilicate glass) |
Ideal uses for this mirror
This primary mirror is an ideal choice in several situations:
- Repairing or renovating an older Newtonian with a damaged or degraded reflective coating
- Upgrading the optics in an existing tube of Sky-Watcher-compatible construction
- Building a custom telescope from scratch
Because this is an original Sky-Watcher component, compatibility with tubes and mounts from this brand is guaranteed without any unnecessary adaptation. The mirror is suitable for visual observers of both planets and deep-sky objects, as well as for demanding astrophotographers who want full control over every element of their optical chain.
Who is this mirror for?
Visual observers
The combination of large aperture and a moderate focal ratio makes this mirror an excellent choice for observing galaxies, nebulae, globular clusters, and planetary details. The Pyrex substrate ensures a stable image even during long observing sessions with significant temperature drops.
Astrophotographers
The f/4.9 focal ratio provides a relatively fast optical system suitable for deep-sky astrophotography. Original Sky-Watcher manufacturing quality ensures consistent performance and precise surface figuring that demanding imaging work requires.
Telescope builders and repairers
If you are building a Dobsonian or a custom Newtonian, this mirror offers a ready-made, proven optical solution. Using an original Sky-Watcher part also simplifies compatibility with a wide range of commercially available secondary mirrors, focusers, and tube assemblies.
