SVBONY SV223 1.25″ 90° Clicklock Dielectric Mirror Diagonal

Product Overview

The SVBONY SV223 1.25″ is a 90° mirror star diagonal with a dielectric-coated mirror rated at more than 99% reflectivity and 1/10λ flatness on an 11.5 mm thick substrate. A Clicklock clamp holds 1.25″ eyepieces, an internal safety stop keeps barrels off the mirror, and the telescope-side barrel carries an M28.5 x 0.6 filter thread. Clear aperture is 25 mm, optical length is approximately 85.5 mm, and it weighs 249 g.

Who It's For

This is a good match if you observe through a refractor, SCT or Maksutov with a 1.25″ eyepiece holder and want a comfortable viewing angle with a quick, secure eyepiece clamp.

Key Features & Design

• Dielectric mirror, >99% reflectivity: 1/10λ flatness on an 11.5 mm thick optical flat.
• Clicklock clamp: a twist-to-lock clamp for fast, centred eyepiece changes.
• Internal safety stop: prevents eyepiece barrels from reaching the mirror.
• Stainless steel compression ring: helps prevent barrels from marring.
• Machined aluminium body: with internal anti-reflection baffling for contrast.
• M28.5 x 0.6 filter thread: on the telescope-side barrel for 1.25″ filters.

Recommended Uses

• Visual observing with refractors and catadioptric telescopes that take 1.25″ accessories.
• Planetary and lunar sessions where frequent eyepiece changes benefit from the Clicklock clamp.
• Compact and travel setups where a 249 g diagonal keeps the load down.

Compatibility and Accessory Notes

• Telescope side: 1.25″ barrel, fits 1.25″ focusers and eyepiece holders; M28.5 x 0.6 thread for 1.25″ filters.
• Eyepiece side: 1.25″ Clicklock clamp.
• Optical length: approximately 85.5 mm.

What's in the Box

• SV223 1.25″ 90° Clicklock dielectric diagonal
• M4 screw (1)
• Dust cap (1)
• Dust plug (1)

Good to Know Before You Order

• Image orientation: the view is upright but mirror-reversed left to right, as with any single-mirror diagonal.
• 1.25″ only: 2″ eyepieces need the 2″ version of the SV223.
• Visual use: a diagonal is for eyepiece observing; imaging cameras usually attach straight-through.

Frequently Asked Questions

Is it difficult to set up?

No. Insert the barrel into your focuser or eyepiece holder, then insert an eyepiece and twist the Clicklock ring to lock it.

Does it take filters?

Yes. 1.25″ filters thread onto the M28.5 x 0.6 telescope-side barrel, so one filter serves every eyepiece.

Why a dielectric mirror?

Dielectric coatings reflect more than 99% of the light and are more durable than standard aluminium coatings.

Will it fit an SCT or Maksutov?

Yes, on any telescope that accepts a 1.25″ barrel, including through an SCT-to-1.25″ visual back.

Bottom Line

In short: a 1.25″ 90° dielectric mirror diagonal with >99% reflectivity, a Clicklock eyepiece clamp and an internal safety stop, at 249 g.