Eyepiece Skywatcher WA-66 20mm 1.25 inch

The Skywatcher WA-66 20mm 1.25 inch eyepiece is a wide-angle optical accessory designed for visual astronomy with amateur telescopes. Offering a 20 mm focal length in a standard 1.25" barrel, this eyepiece expands the apparent field of view and improves viewing comfort for lunar, planetary and many deep-sky targets. Its compact construction and straightforward fit make it compatible with most telescopes and diagonals that accept 1.25" eyepieces.

Advantages

The WA-66 design provides a wider apparent field compared with standard Kellner-style eyepieces, helping observers capture more of the sky at once and easing target acquisition. Its 20 mm focal length delivers moderate magnification suitable for both lunar and planetary detail as well as brighter nebulae and star clusters. The 1.25" barrel ensures broad compatibility and simple installation, while the compact, lightweight housing supports easy transport and quick swapping between eyepieces.

Suitable for

• Visual observation of the Moon and planets
• Wide-field views of open star clusters and brighter nebulae
• Casual astrophotography with DSLR or smartphone through eyepiece projection (eyepiece projection adapters required)
• Portable and backyard telescope setups where a comfortable field of view is desired

Key specifications

• Focal length: 20 mm
• Barrel diameter: 1.25 inches
• Optical type: wide-angle eyepiece (WA-66 design)
• Typical uses: lunar, planetary and bright deep-sky observation
• Physical form factor: compact, lightweight eyepiece housing

How to use

Insert the eyepiece into a 1.25" focuser or star diagonal until it seats securely, then tighten the focuser thumbscrew or clamp to hold it in place. Use the telescope’s focuser to achieve a sharp image; start with low eyepiece magnification and adjust focus slowly. For best results, ensure the telescope is properly collimated and thermally stable before observing. When switching eyepieces, handle optics by the barrel to avoid touching lens surfaces.

Recommendations

For improved viewing comfort, pair the WA-66 20mm with a stable mount and allow the telescope to reach ambient temperature. Use a diagonal with sufficient clearance if observing objects near the zenith and consider an eyepiece cap when storing to protect the optics.