Pentax XW-20 Eyepiece

The Pentax XW-20 Eyepiece is a premium wide-angle eyepiece designed for serious astronomical and terrestrial observers who demand exceptional optical performance, viewing comfort, and all-weather reliability. With its long focal length and advanced optical engineering, the XW-20 is ideal for deep-sky observation, wide-field scanning, and extended viewing sessions.

Wide, Immersive Field of View

Delivering a 70-degree apparent field of view, the Pentax XW-20 provides an immersive observing experience that allows large celestial objects, star fields, and nebulae to remain comfortably framed. This expansive field is paired with a generous 20mm eye relief, making the eyepiece extremely comfortable to use, including for observers who wear glasses.

Advanced Lanthanum Optical Design

At the core of the XW-20 is a high-performance optical system using high-refraction, extra-low-dispersion lanthanum glass elements. This design minimises chromatic aberration, improves edge sharpness, and delivers a well-balanced, high-contrast image across the entire field of view. The eyepiece is also engineered to reduce blackout and kidney-bean effects by compensating for spherical aberration of the exit pupil.

Exceptional Light Transmission and Contrast

All air-to-glass surfaces feature Pentax’s original multi-layer coatings, while bonded elements use advanced partial coatings to maximise light transmission. This results in excellent brightness and contrast, with transmission exceeding 90% across the visible spectrum and peaking at approximately 96% at 550nm for vivid, natural-looking images.

Precision Internal Baffling

To further enhance image quality, the Pentax XW-20 incorporates precision-positioned internal diaphragms developed using advanced computer simulation technology. These effectively suppress internal reflections and stray light, producing darker backgrounds and improved contrast, particularly beneficial for deep-sky observation.

Weather-Resistant and Highly Versatile

Built for real-world observing conditions, the Pentax XW-20 features JIS Class 4 weatherproof construction, allowing confident use in damp environments, light drizzle, or heavy night dew. The 31.7mm (1.25-inch) barrel ensures compatibility with a wide range of telescopes and Pentax spotting scopes, while removal of the rotatable eyecup reveals a 43mm threaded interface for camera adapters and projection accessories.

Combining wide-field immersion, long eye relief, advanced coatings, and rugged weather-resistant construction, the Pentax XW-20 Eyepiece is an outstanding choice for observers seeking premium optical performance and long-term viewing comfort.