SVBONY SV197 1.25″ Cheshire Collimating Eyepiece for Newtonians

Product Overview

The SVBONY SV197 is a 1.25″ Cheshire collimating eyepiece for aligning the mirrors of a Newtonian reflector. It combines a sight tube with steel crosshairs and a reflective Cheshire face, so you can centre the secondary mirror under the focuser and then adjust the primary until its reflection is centred. The body is CNC-machined aluminium, black oxidised, measures 141 × 41 × 32 mm and weighs 156 g.

Who It's For

This is a good match if you own a Newtonian or Dobsonian and want a passive collimation tool that needs no batteries and does not depend on the focuser's own alignment the way a laser can.

Key Features & Design

• Steel crosshairs for centring the secondary and primary reflections.
• 1.25″ (31.75 mm) barrel for 1.25″ focusers or 2″ adapters.
• CNC aluminium body, black oxidised, with an inner structure that reduces stray reflections.
• No batteries or electronics.

Recommended Uses

• Routine collimation of Newtonian and Dobsonian telescopes before an observing or imaging session.
• Checking alignment after transport.
• Verifying a laser collimator's result.

Compatibility and Accessory Notes

• Telescope type: Newtonian reflectors, as SVBONY specifies.
• Focuser: 1.25″ directly; 2″ focusers with a 2″-to-1.25″ adapter.
• Fast and slow scopes: SVBONY notes that on fast telescopes (around f/5 and faster) the correctly collimated view sits slightly off-centre, while on slower telescopes it is more centred and easier to read.

Good to Know Before You Order

• Daylight or a lit room helps: a Cheshire relies on ambient light entering its side port to illuminate the reflective face.
• Net weight 156 g.

Frequently Asked Questions

Is it difficult to set up?

It slides into the focuser like an eyepiece. Collimation itself takes a little practice: centre the secondary under the crosshair, then turn the primary adjusting screws until the primary's reflection sits centred in the secondary.

Do I need batteries?

No. It is a passive optical tool.

Does it work on refractors or SCTs?

SVBONY lists it for Newtonian telescopes.

Bottom Line

In short: a 1.25″ CNC aluminium Cheshire collimating eyepiece with steel crosshairs, for centring the secondary and primary mirrors of a Newtonian without batteries or electronics.