William Optics Dura Bright 90° diagonal mirror 1.25″
Advanced dielectric coating technology
The premium William Optics Dura Bright diagonal mirror represents a significant technological advancement in astronomical optics. This 90-degree diagonal with 1.25″ diameter utilizes advanced dielectric coating technology that ensures exceptional 99% reflectivity, providing astronomers with unmatched image quality when observing celestial objects.
At the heart of this diagonal mirror is the Dura Bright dielectric surface, which represents a major step forward compared to traditional aluminum or silver coatings. While standard mirrors achieve reflectivity around 90-95%, this mirror with 99% reflectivity practically eliminates light loss. This results in significantly higher contrast and sharpness when observing planets, the Moon, double stars, and other demanding objects where every photon counts.
Precision optical surface
The optical surface is crafted with extreme precision better than lambda/10, meaning surface irregularities do not exceed one-tenth of a wavelength of light. This precision ensures minimal light scatter and maximum fidelity in image transmission from the telescope's primary mirror to the eyepiece.
The mirror substrate has a thickness of 12mm, providing exceptional mechanical stability and resistance to deformations caused by temperature changes or vibrations. This robust construction is crucial for maintaining precise optical alignment during long observation sessions, where even minimal movement can affect image quality.
Technical specifications
| Optical coating |
Dura Bright dielectric |
| Reflectivity |
99% |
| Mirror diameter |
1.25″ |
| Mirror thickness |
12mm |
| Surface accuracy |
Better than λ/10 |
| Angle |
90 degrees |
| Threading |
1.25″ standard |
Premium construction materials
The diagonal body is manufactured from high-quality machined aluminum with elegant side panels made from genuine carbon fiber. This carbon fiber design not only gives the mirror a premium appearance but also contributes to its lightness and thermal stability. Carbon fiber has lower thermal expansion than aluminum, helping to keep optical components in precise position even during temperature changes.
William Optics has paid considerable attention to every construction detail. Large, knurled thumbscrews are easily operated even when wearing gloves during cold winter nights. The securing mechanism for eyepieces or adapters uses compression rings that evenly distribute pressure and protect delicate eyepiece barrels from damage.
Advanced internal design
The internal construction includes a sophisticated system of anti-reflection baffles that eliminate parasitic light and reflections within the diagonal. These baffles are strategically positioned to capture scattered light that could otherwise reduce image contrast. Additionally, safety stops are implemented to prevent 1.25″ eyepiece barrels from hitting the mirror surface directly.
Exceptional performance for demanding observations
This diagonal mirror is specifically designed for demanding applications where every image detail is critical. When observing planets like Jupiter, Saturn, or Mars, where fine surface details and atmospheric structures are important, the 99% reflectivity provides significantly better contrast than standard diagonals. High contrast is essential for resolving subtle features such as bands on Jupiter, gaps in Saturn's rings, or polar caps on Mars.
Similarly, when observing the Moon, this mirror reveals finer details of craters, mountain ridges, and lunar seas thanks to minimal optical losses. For double star enthusiasts, it enables better separation of close stellar pairs due to higher contrast between stars and the sky background.
Universal compatibility and durability
The diagonal features standard 1.25″ threading on both the telescope side and eyepiece side, ensuring compatibility with most modern astronomical telescopes and a wide range of eyepieces. Precise mechanical construction guarantees stable connection without play or inaccuracies that could affect focusing or image stability.
Designed specifically for the highest class of telescopes, this mirror can utilize the full potential of quality optical systems. Its construction eliminates common problems of cheaper diagonals, such as optical aberrations, mechanical instability, or rapid wear of moving parts.
Perfect for portable and stationary setups
Compact dimensions and relatively low weight make this mirror an ideal choice for both stationary observatories and mobile astronomers who value equipment portability. The robust construction withstands regular transport and handling while maintaining its optical precision for years of use.
The diagonal is particularly effective for planetary observation, where the superior light transmission and contrast enhancement reveal subtle atmospheric details and surface features that remain hidden with standard diagonals. The advanced optical coatings maintain their performance characteristics across a wide temperature range, making this diagonal suitable for year-round astronomical observations.
Applications and recommended use
- High-resolution planetary observation
- Detailed lunar surface studies
- Double star separation
- Solar system object photography
- Deep sky observation enhancement
- Professional and advanced amateur astronomy
