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William Optics 40mm Swan Eyepiece - 2"


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  • Focal Length: 40 mm
  • Barrel Size: 2-inch
  • 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-inch 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-inch 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-Inch Eyepiece
    • Eye Guard
    • Dust Caps


Product Reviews

Customer Reviews
4.8 Based on 14 Reviews
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Filter Reviews:
    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.

    Very good 2" 40mm EP

    This was my first buy of a Williams Optics EP. I was a little anxious about quality given the low price. I can tell you that this is an excellent EP providing wide sharp crisp views. I highly recommend this EP. As an aside - it also looks great with excellent build quality.

    Efrem A.
    Magnificent viewing

    This eyepiece was purchased to give my new edge hd 8 a wide field for low power viewing(at least more than my Q70 32mm)wow!!This should be the first upgrade for SCT telescopes along with 2 inch diagonal.Clarity and sharpness and depth of field is on par with my Tele vue Delos 17.3 of course with a wider field of view.A must have eyepiece!!!!