Sky-Watcher secondary mirror - Newtonian reflector 200/1200 200mm
If you are looking for a reliable replacement or upgrade secondary mirror for your Newtonian telescope with a 200mm primary mirror, this Sky-Watcher secondary mirror for 200mm Newtonian reflector is exactly what you need. It features high-quality optical surface workmanship, which is essential for achieving a sharp and contrasty image - whether you are observing planets, double stars or deep-sky objects.
Compatibility and intended use
This secondary mirror is designed primarily for Sky-Watcher optical tubes in the 200/1200 configuration, meaning a focal length of 1200mm (f/6). It can also be used in telescopes with a focal length of 1000mm; however, for the 200/1000 (f/5) configuration, the larger secondary mirror variant - specifically model SW-5513 with a slightly larger ellipse axis - will be more suitable, as it better covers the light cone of the faster optical system.
For f/6 optical tubes, this mirror is the ideal choice. It does not unnecessarily increase the central obstruction, which has a positive effect on image contrast.
Why the size of the secondary mirror matters
The secondary mirror of a Newtonian reflector is elliptical, and its correct size directly affects two key properties of the telescope:
- Light throughput - the size of the fully illuminated field of view
- Central obstruction - the proportion of the aperture area covered by the secondary mirror
A smaller secondary mirror means lower central obstruction and better contrast - ideal for planetary observation. A larger secondary mirror, on the other hand, provides a uniformly illuminated field for astrophotography and observation of extended objects.
Optical quality and coating
The secondary mirror only reflects light towards the focal point, but its optical quality - above all the flatness of the reflecting surface and the quality of the surface finish - has a direct influence on the final image. A high-quality surface with reflective coating ensures minimal light scatter and maximum contrast transmission.
Sky-Watcher standardly uses high-reflectivity coatings on its mirrors, additionally protected by a protective overcoat for long service life even with regular cleaning.
Applications - replacement, DIY build and upgrade
This replacement secondary mirror is an excellent choice not only when replacing a damaged original, but also as a foundation for a DIY Newtonian reflector build or for upgrading an older optical tube. The dimensions and mounting system correspond to standard Sky-Watcher components, making installation into the original secondary mirror holder straightforward.
Choosing the right variant
If you are unsure which variant is most suitable for your optical tube, we recommend comparing the parameters with model SW-5513 and choosing according to the actual focal length of your primary mirror:
| Configuration |
Focal length |
Focal ratio |
Recommended secondary mirror |
| 200/1200 |
1200mm |
f/6 |
This model |
| 200/1000 |
1000mm |
f/5 |
SW-5513 (larger ellipse axis) |
Summary
Overall, this is a quality optical component for a 200mm Newtonian reflector that will help you keep your telescope in top condition or serve as the foundation for a new project. Precise optical surface, high-reflectivity coating and compatibility with standard Sky-Watcher mounting systems make this mirror a reliable choice for both casual observers and more demanding users.
