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William Optics 1.25" Swan Series Eyepiece - 9mm

5.0 (1 Reviews) Read Reviews Write Review
Brand William Optics
Part Number E-SWA09
Availability available

Product Info

Manufacturer Description

The Swan eyepieces are super wide angle designs with a 72° 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 multicoated 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 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, 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 1.25" 9mm SWAN EP's panoramic views at 72 deg. FOV will leave you speechless!  A premium eyepiece at a fraction of the cost its worth!

Super Wide FOV
Outstanding super-wide field of view: 72 deg. FOV
Fully Multicoated lenses for excellent transmittance.
Reduced chromatic aberration.
Improved contrast compared to similar EPs.

Great Contrast
Internally fully blackened (lens edges and internal spacers).
No flaring or ghosting on high-contrast objects.

Light and Easy
Soft rubber eyecup.
Long eye-relief: 12mm.
No internal reflections, kidney beaning or other distracting distortions.

Terrific Fit and Finish
High-resistance anodized black barrel.
Smooth design for no hook up in your focuser.
Threaded for use with 1.25" filters.


5.0 (Based on 1 Reviews) 100% of reviewers recommended this product.
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      User Notes:
      Review by Scott A.
      Aug 15, 2017

      5.0 9mm eyepieces ... really terrific in my binoviewer!




      I have now used these William Optics 9mm eyepieces in my William Optics binoviewer -- took a few days to get clear skies! -- and they have produced outstanding views! Highly recommended!

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Apparent Field of View 72°
      Barrel Size 1.25" (31.7mm)
      Bolt Case Included Yes - Free Agena Eyepiece Container
      Bolt Case Size Agena 42x60mm
      Coatings Fully Multi-Coated
      End Caps 2
      Eye Relief by Design 12mm
      Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6)
      Focal Length 9mm
      Lens Elements 5
      Lens Groups 4
      Parfocal Yes
      Blackened Lens Edges Yes
      Manufacturer William Optics
      Eyepiece Focal Length 5.1mm - 10mm
      Eyepiece Field of View 71 - 80 degrees
      Eyepiece Series William Optics SWAN
      Barrel Type Tapered barrel
      Eyepiece Weight 2.47oz (70g)