William Optics 40mm Swan Eyepiece - 2"

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


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  • Regular price $118.00

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William Optics 40mm Swan Eyepiece - 2"

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.



Dust Caps IncludedYes
ER20mm or More
Eye Guard IncludedYes
Eye Relief28mm
Eyepiece OpticsWide Angle
Field of View72 degrees
Focal Length40mm
FoV 79 Degrees
Free ShippingYes
Lens Elements & Groups5 elements & 4 groups
ManufacturerWilliam Optics
ModelWilliam Optics Swan
Warranty2 Year Warranty



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


Customer Reviews
4.8 Based on 13 Reviews
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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!!!!

John S.
40mm SWAN

I purchased this eyepiece in April 2018 and absolutely love it! Superb optical quality to say the least. I have an 8se, a SW Pro 100 ED, and a Parallax 14.5 Newtonian and it is without a doubt my favorite eyepiece, especially with the 14.5. I find myself slewing from one star cluster to the next all night long.