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William Optics 40mm Swan Eyepiece - 2"


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  • Focal Length: 40 mm
  • Barrel Size: 2"
  • Apparent FoV: 72-degrees
  • Eye Relief: 28 mm


Product Details

  • The Swan eyepieces are super wide angle designs with 72-degree apparent field of view. They use simple but sophisticated five-lens optical systems for generally higher contrast than the more complicated optical designs used in some other super wide angle eyepieces that use up to eight lenses. All lenses are fully multi-coated for high light transmission. Lens edges and internal field stops are blackened to reduce internal reflections and improve contrast. The eyepiece rubber grip ring is useful for safer handling of the heavier 2" eyepieces in cold weather when wearing gloves. The eyepieces have soft roll down rubber eyecups for eyeglass use. They can be used for all types of observing, both day and night!

    The William Optics SWAN 40 mm Eyepiece has soft roll down rubber eyecups for eyeglass use. They can be used for all types of observing, with all telescope types, but they are recommended for use with focal ratios up to f/6 and above. Dust caps are provided for both ends of each eyepiece.

    This 4-element super-wide angle 40 mm SWAN EP's panoramic views at 72 deg. F.O.V. will leave you speechless!


    William Optics 40 mm SWAN Eyepiece Features


    • Fully Multicoated lenses for excellent transmittance..
    • Reduced chromatic aberration.
    • Improved sharpness and contrast throughout the field.
    • No internal reflections, kidney beaning, pin-cushion or other distortions.
    • Smooth design for no hook up in your focuser.
    • Threaded for 2" filter usage.
    • Rubber grip ring for safe, comfortable handling.


  • specifications

    Dust Caps IncludedYes
    Eye Guard IncludedYes
    Eye Relief28mm
    Field of View72 degrees
    Focal Length40mm
    Free ShippingYes
    Warranty2 Year Warranty
  • included items


    • William Optics Swan 40 mm 2" Eyepiece
    • Eye Guard
    • Dust Caps


Product Reviews

Customer Reviews
4.8 Based on 16 Reviews
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  • AFOV
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United States United States

This is my new favorite eyepiece

I absolutely love this eyepiece for viewing clusters in my C8 2032mm f/10. As other reviewers have mentioned, there is some edge distortion but what else do you expect with a wide angle lens at this price point. Its clear, slightly contrasty, which is nice. and at 40mm it's easy to focus. I especially love that the viewing angles are great. I dont have to move my head a bunch to find a sweet spot... AT ALL.

United States United States

Excellent Eyepiece!

I read reviews about this eyepiece in Cloudy nights and decided to go for it because of the longer eye relief since I wear glasses when observing. I used this with my 8" Meade ACF SCT and a 2" durabright diagonal. This gave an extremely good bright view. Stars are pin point and has nice contrast. I did notice a very light blue-ish tint. Stars are a hint bluer but not bad, Orange/ red stars still look normal but white Stars are a bit more blue when comparing with a few other eyepieces. This did not bother me at all about the eyepiece, I just thought I would point that out. For the price, this is an excellent quality low magnification eyepiece and the 72° AFOV is perfect in an 8" sct for scanning the sky. The build quality and weight is also very nice and comfortable to handle. This eyepiece is definitely a keeper. I highly recommend this eyepiece.

thomas b.
United States United States


Great job with everything.

A OPT Telescopes Customer
United States United States

Unbeatable performance for price point

After careful inspection of the glass elements, and was unable to spot a single piece of dust. This eyepiece was very well made, and delivers fantastic optical performance. The field is not as flat as I would like it to be, but some coma is expected when ultra wide-angled pieces are paired with fast Mak-Newts. I will be buying William Optics again.

Cindy R.
United States United States

40mm swan

Excellent optics. Surpassed my expectations.

United States United States

Nice eyepiece

I really like this eyepiece. I wanted something that has good quality optics and offered a large field of view. It does both - very happy with this eyepiece.