Sky-Watcher 90° 1.25" Erect Image Diagonal

The Sky-Watcher 45° 1.25" Erect Image Diagonal is a high-quality accessory designed to provide a natural, upright, and non-reversed image for advanced telescope systems. By utilizing a 1.25" erecting prism, it eliminates the confusing image inversion typically found in astronomical optics, ensuring that objects appear exactly as they do to the naked eye. This makes the diagonal an essential tool for astronomers who want accurate representation and clear, crisp views during their observation sessions, especially when transitioning between celestial and terrestrial targets.

Designed with a 45° viewing angle, this prism offers superior ergonomics and convenience, allowing for a relaxed posture during long observation periods. Its user-friendly design features a 1.25" adaptation for easy attachment of a wide range of compatible eyepieces, significantly enhancing the versatility of high-end telescope systems. Whether you are a dedicated enthusiast or an advanced observer, this diagonal provides the usability and precision required for a truly immersive and comfortable viewing experience.

Product Features in Detail

Natural Perspective with Amici Prism Technology

The core of this diagonal is a precision-ground Amici roof prism. Unlike standard mirrors that flip the view, this prism correctly reorients the light path so that images are both vertically upright and horizontally correct. This allows you to use your high-performance telescope as a powerful spotting scope, viewing the world exactly as you see it with the naked eye.

Ergonomic 45° Observation Angle

Designed specifically for terrestrial and low-horizon viewing, the 45-degree tilt provides the most comfortable ergonomic position for the observer. When your telescope is pointed horizontally toward a distant landscape or bird, this angle allows you to look down into the eyepiece at a natural incline, significantly reducing neck strain during extended sessions.

Seamless "Plug-and-Play" Integration

Engineered for convenience, this diagonal features a universal 1.25" (31.7mm) barrel. It can be installed in seconds by simply sliding it into the focuser of any standard refractor or Schmidt-Cassegrain telescope. No tools or complex adapters are required to transition your instrument from an astronomical "galaxy hunter" to a high-end nature observer.

Intuitive Tracking and Navigation

One of the biggest hurdles in daytime observation is the "reversed motion" of standard telescopes. By providing a non-reversed image, this diagonal ensures that when you move the telescope left, the view moves left. This natural feedback loop is essential for instinctively tracking moving targets like wildlife, ships, or aircraft.

High-Contrast, Multi-Coated Optics

To ensure that your view remains bright and vivid even in daytime glare, the prism surfaces are treated with high-quality optical coatings. These coatings increase light transmission and reduce internal reflections, delivering the crisp, high-contrast imagery necessary to resolve fine details like the plumage of a bird or the lettering on a distant vessel.

Robust Construction for High-End Systems

Specifically tailored for use with premium telescope systems, this diagonal is built with a durable housing and a chrome-plated barrel. The secure mechanical fit ensures that even heavier wide-field eyepieces remain perfectly aligned, while the rugged build quality ensures the delicate internal prism remains protected during travel and field use.