Description
Product Overview
The Astromania 1.25″ 90° mirror diagonal is engineered for astronomers who value ergonomic design and optical precision. Constructed from a robust metal barrel, the diagonal securely seats in the focuser, minimizing wobble during long observation sessions. The mirror features a multi‑layer protective coating that resists tarnish and extends the product’s lifespan. With a compact footprint of 4.42 x 2.8 x 2.11 inches and a lightweight of just 4.4 ounces, it adds minimal load to your mount while delivering a true 90‑degree image rotation. The unit accepts standard 1.25″ eyepieces and includes a 1.25″ filter thread, allowing seamless integration of nebula or light‑pollution filters.
Usage
Designed for refractor and Cassegrain telescopes, this diagonal excels in both backyard stargazing and field observations. Its 90° angle lets users view the sky from a comfortable, head‑up position, reducing neck strain during extended sessions. The diagonal is unsuitable for Newtonian reflectors, ensuring optimal performance where the optical path aligns with its design. Whether you are imaging deep‑sky objects, conducting planetary work, or simply enjoying a casual night under the stars, the Astromania diagonal provides a reliable, easy‑to‑install solution.

Why Choose Us
Astromania combines decades of optical engineering with meticulous material selection. The metal barrel offers superior rigidity compared to plastic alternatives, while the protective mirror coating safeguards against oxidation and scratches. Each unit undergoes rigorous quality testing to meet a 4.2‑star rating from over 50 verified customers. Backed by a reputable manufacturer and a consistent best‑seller rank (#12 in Telescope Diagonals), this product delivers dependable performance without the premium price tag.
Key Features
- 90° mirror design for comfortable, head‑up viewing
- Durable metal barrel ensures stable mounting
- Protective multi‑layer coating extends mirror life
- Standard 1.25″ eyepiece and filter thread compatibility
- Optimized for refractor and Cassegrain telescopes
FAQ
Can this diagonal be used with a Newtonian reflector?
No, the optical geometry of Newtonian reflectors is not compatible with the 90° mirror design of this product.
What eyepiece sizes are supported?
The diagonal accepts any standard 1.25″ eyepiece, making it versatile for a wide range of magnifications.
Is the mirror coating prone to degradation over time?
The protective coating is engineered to resist tarnish and scratches, providing a long service life under normal observing conditions.
How does the diagonal attach to the focuser?
The metal barrel slides securely into a standard 1.25″ focuser slot and locks in place with the provided set screw.
Does the product include any warranty?
Astromania offers a one‑year limited warranty covering manufacturing defects.




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