The SVBONY SV221 1.25″ 90-degree Mirror Diagonal is a lightweight, practical diagonal designed for refractor telescopes, improving viewing comfort by redirecting the optical path through a right-angle mirror. It is suitable for both terrestrial observation and astronomical viewing.

Key Features

• 90° Comfortable Viewing Angle
  Right-angle design allows relaxed viewing without awkward body positions, ideal for longer observing sessions.
• Aluminium-Coated Mirror
  High-quality mirror surface provides over 92% reflectivity for bright, clear images.
• Brass Compression Ring Clamp
  Secure brass pressure ring holds eyepieces firmly while preventing scratches or marring.
• 1.25″ Filter Compatibility
  Built-in M28.5 × 0.6 filter thread allows easy use of standard 1.25″ astronomical filters.
• Lightweight & Durable Construction
  Combination of aluminium barrels and reinforced ABS housing offers strength without unnecessary weight.

Mirror Diagonal Image Orientation

As a mirror diagonal, the SV221 produces a mirror-reversed image (left-right inversion), which is normal for mirror diagonals and commonly used in astronomical observation.

Enhanced Aluminium Die Mirror Housing

The mirror assembly is housed in an aluminium die-cast structure designed to maintain optical alignment and maximise light throughput for consistent image quality.

Brass Compression Ring Protection

The integrated brass compression ring applies even pressure around the eyepiece barrel, preventing damage while ensuring a secure, wobble-free fit.

Comfortable 90° Viewing Design

The 90-degree viewing angle significantly improves ergonomics when observing objects high in the sky or during extended viewing sessions.

Typical Applications

• Astronomical observing with refractor telescopes
• Casual terrestrial viewing
• Bird watching and landscape observation
• Beginner and portable telescope setups

What’s Included

• SV221 1.25″ 90° mirror diagonal
• 3 × M3 mounting screws
• Dust cap
• Dust plug

Key Specifications

• Diagonal size: 1.25″
• Viewing angle: 90°
• Optical type: Mirror diagonal
• Mirror reflectivity: >92%
• Filter thread: M28.5 × 0.6
• Eyepiece clamp: Brass compression ring

Compatibility Notes

• Designed for refractor telescopes
• Produces mirror-reversed images (normal for mirror diagonals)
• Not an erect or correct-image diagonal