The William Optics SWAN 72° 40mm Eyepiece is a premium optical accessory designed for astronomical telescopes. This wide-angle eyepiece offers a generous 72-degree apparent field of view, providing immersive views of large celestial objects and star fields. With its long 40mm focal length, it's ideal for low-magnification, wide-field observations.
Requires a telescope with a 2-inch focuser or eyepiece adapter. Check your telescope's specifications before purchasing.
Optical Design
Features a sophisticated multi-element design optimized for wide-field viewing. The SWAN (Super Wide Angle) series utilizes high-quality glass and coatings to deliver sharp, high-contrast images across its expansive field of view.
Field of View
Offers an impressive 72-degree apparent field of view, providing a spacious and immersive observing experience. This wide field is particularly advantageous for observing large deep-sky objects, star clusters, and expansive nebulae.
Focal Length:
With a 40mm focal length, this eyepiece provides low magnification and a wide true field of view when used with most telescopes. This makes it excellent for scanning the Milky Way, observing large open clusters, or framing extended nebulae.
Eye Relief
Generous eye relief allows for comfortable viewing, especially beneficial for eyeglass wearers. The exact eye relief specification should be verified with the manufacturer for the most current information.
Construction
Built with high-quality materials, likely including a durable metal housing and rubber eye guard for comfort. The 2-inch barrel ensures a secure fit in compatible focusers and maximizes light throughput for the best possible views.
Coatings
Utilizes multi-layer anti-reflection coatings on all air-to-glass surfaces to maximize light transmission and reduce glare, ensuring high-contrast views with accurate color rendition.
Versatility
While particularly well-suited for refractors and Cassegrain-type telescopes, this eyepiece can be used with a wide variety of telescope designs. Its low magnification makes it an excellent choice for finding and framing targets before switching to higher-power eyepieces for detailed observation.
