William Optics 40 mm Super Wide Angle 2" Eyepiece
William Optics SWAN 40mm 2" Eyepiece
In search of a high quality wide field eyepiece with an affordable price tag? This William Optics SWAN eyepiece is the perfect solution! Superb optical power across the entire 72° field of view is sure to take your observing sessions to the next level.
The wide 72° apparent field of view of this William Optics SWAN eyepiece delivers a highly immersive experience under the stars. This enveloping perspective makes it feel like you’re floating through space, while the 40 mm focal length fills the frame with large deep sky objects. With the William Optics SWAN, chromatic aberration is well-corrected and the fully multicoated lenses ensure peak light transmission for the best views. Soft rubber eyecups, zero internal reflections, and built-in threads for 2” filters make this a must have instrument within your observing toolkit!
William Optics SWAN 40mm Eyepiece At a Glance
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Incredible Performance Without Breaking the Bank
This William Optics SWAN 40 mm 72° eyepiece delivers stark, high contrast views at a highly affordable rate. Be amazed by vast nebulous sights and beautiful detail within your eyepiece. Read on as we take a closer look at the features of this William Optics eyepiece below!
Expansive Views with the 72° AFOV
The super-wide 72° apparent field of view creates an enveloping sensation when observing the night sky. This highly immersive perspective is wonderful for achieving that “wow” factor when peering through your eyepiece. The eyepiece lenses are fully multicoated to ensure peak light transmission to your eye, and the precise lens alignment ensures outstanding chromatic aberration correction. Sharp, beautifully detailed sights are yours for the taking!
Outstanding Contrast
While observing the night sky, optics that foster high contrast mean the difference between lackluster views and striking, unforgettable sights. This William Optics SWAN 40 mm eyepiece has fully blackened internal lens edges and spacers to put a damper on internal reflections, flaring, and ghosting. This is particularly useful when observing bright objects such as our Moon, helping you focus more on the outstanding detail presented within your eyepiece and less on intrusive reflections.
Top-Tier Construction
Built with quality in mind, William Optics constructs their SWAN 40 mm eyepiece to deliver the best user experience possible. Soft rubber eyecups and the extra-long eye relief of 28 mm ensures the utmost comfort when observing the cosmos. The smooth, perfectly cylindrical barrel inserts seamlessly into your focuser for an effortless, premium experience for the user. At the bottom of your eyepiece, you’ll find threads for attachment of your favorite observing filters as well. The black anodized body is resistant to scratches, offering top quality for years to come.
40mm Focal Length
To maximize your telescope’s light gathering power, it’s important to find the right eyepiece focal length for the best views possible. The ratio of telescope focal length to eyepiece focal length is your system’s magnification, helping you determine not only what celestial objects can be viewed but how clear your image will be as well. This William Optics SWAN eyepiece has a focal length of 40 mm. When paired with a 1200 mm focal length telescope, the resulting magnification will be 1200/40 = 30x magnification. This low magnification is wonderful for viewing a wide variety of large deep space objects, even under subpar seeing conditions. For a more in-depth look at this topic, be sure to check out our Telescope Eyepiece Guide found within our Astronomy Hub.
Understanding Exit Pupil
Just as magnification is an important factor to consider when choosing an eyepiece, calculating your system’s exit pupil is necessary in determining what’s available for viewing. Exit pupil is the diameter of the beam of light exiting your eyepiece, with the larger the diameter, the brighter the image. Exit pupil is calculated with the following equations: Exit Pupil = Telescope Aperture (mm) ÷ Magnification, or Exit Pupil = Eyepiece Focal Length ÷ Telescope Focal Ratio. This William Optics SWAN 40 mm eyepiece paired with a standard f/6 scope will yield an exit pupil of ~7 mm , making it wonderful for observing dim deep sky objects! Our Telescope Eyepiece Guide provides a deeper insight into the importance of exit pupil.
Astronomy Hub: Your one-stop-shop for Astronomy Knowledge!
Our Gear Experts have compiled a wealth of information to help you get the most out of your telescope! Below you’ll find links to articles, videos and "how-to" guides. Just one more reason that our Astronomy Hub is a one-stop-shop for all your astronomy and astrophotography needs!
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