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William Optics 20mm Swan Eyepiece - 1.25"


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Product Details

  • William Optics 20 mm SWAN Eyepiece:

    The Swan eyepieces are super wide angle designs with 72-degrees of 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 20 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. A soft protective drawstring-equipped velvet storage bag is standard equipment with each.

    This 5-element super-wide angle 2 mm SWAN eyepieces' panoramic views at 72-degrees field-of-view will leave you speechless!



    William Optics 20 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 filter usage.
    • Rubber grip ring for safe, comfortable handling.


    William Optics Product Number: SWAN20


  • specifications

    Dust Caps IncludedYes
    Eye Guard IncludedYes
    Eye Relief17mm
    Field of View72 degrees
    Focal Length20mm
    Free ShippingYes
    Warranty2 Year Warranty

Product Reviews

Customer Reviews
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    David A.

    A Mini portal into space

    This is an interesting eyepiece, that I would say is a mini portal to space, much like the Naglers portal to space, where the SWAN is 72° and the Nagler is 82°. I gave it 4 stars because the eye relief is the limiting factor. You need to put your eye pretty close to the eyepiece in order to get a fairly good view. You do need to move your eye around to get the full effect of the mini-portal effect. There is minimal pin cushion at the edge of the field. I would put the good field of view at about 3/4 and the outer 1/4 is a tiny bit blurry, with noticeable astigmatism, but not enough to totally degrade the viewing experience. I notice that when viewing the planets, it is a comfortable field of view but when viewing the Sun, I do notice that my eye needs to be closer to the eyepiece to get a good view. All in all, I like this eyepiece and the field of views is pretty amazing.