Eyepiece for Telescope Celestron 94182, replacement optical eyepiece, black

The Celestron Cheshire Collimation Eyepiece (model 94182) is a replacement 1¼" eyepiece designed to assist with precise optical alignment of Newtonian reflectors and to aid alignment of Schmidt-Cassegrain telescopes. Supplied in black, it fits standard 1¼" focusers or diagonals and is intended as an optical accessory or spare viewing lens for observational astronomy.

Advantages

The Cheshire eyepiece provides a simple, mechanical method for checking and adjusting telescope collimation without electronics. Its combination of a small alignment aperture at one end and thin crosshairs at the other end enables accurate centring of the secondary mirror and fine tuning of the primary mirror alignment. Lightweight and easy to install, it serves as a practical spare eyepiece for general-purpose use.

Suitable for

• Precise collimation of Newtonian reflector telescopes
• Assisting alignment of Schmidt–Cassegrain telescopes
• Use as a replacement 1¼" eyepiece for observational astronomy
• Routine maintenance and field collimation checks

When it may not be suitable

The Cheshire collimation eyepiece is not a magnifying or imaging eyepiece and therefore is not intended for visual observation of celestial objects. It does not contain electronic or laser alignment features, so users seeking automated or illuminated collimation aids may prefer other tools. It is designed specifically for 1¼" focusers and may not fit eyepiece holders of different diameters without an adapter.

Key specifications

• Type: Cheshire collimation eyepiece / replacement eyepiece
• Focuser size: 1¼" (fits standard 1.25 inch focusers or diagonals)
• Colour: Black
• Compatible telescope types: Newtonian reflectors; can assist with Schmidt–Cassegrain alignment
• Origin: China

How to use

Insert the Cheshire eyepiece into the telescope's 1¼" focuser or diagonal as you would a normal eyepiece. Look through the end with the crosshairs while observing the view through the small alignment aperture; adjust the secondary mirror and then the primary mirror until the reflections and crosshair alignment indicate proper collimation. Follow your telescope manufacturer's collimation procedure for step-by-step mirror adjustments.

What to consider before purchase

• Ensure your telescope accepts 1¼" eyepieces or obtain an appropriate adapter.
• Confirm you need a mechanical Cheshire-style collimation tool rather than an illuminated or laser collimator.
• Check compatibility with Newtonian and Schmidt–Cassegrain mirror alignment processes.

Usage recommendations

Use the Cheshire eyepiece on a stable mount and perform collimation in a well-lit area initially to familiarise yourself with mirror reflections; verify final alignment on-sky by checking star shapes at high magnification.