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William Optics Star71 Four Element f/4.9 Imaging Refractor w/2.5" Focuser - A-WO71-II

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SKU: WYO-A-WO71-II

William Optics Star 71 Four Element f/4.9 Imaging Refractor


William Optics designed this unique refractor for astro-imagers who want a portable, high quality telescope that will produce stunning images of the universe. The 71 mm f/4.9 optics of the Star-71 are made of FPL-53 glass for color-free performance, and consist of four elements in three groups in a 3-1-1 patented configuration. This design produces pinpoint images to the edge of a 45 mm full frame imaging circle!

The 2.5” dual-speed rack & pinion focuser terminates in a male M48 thread to easily accept the photo adapter of your choice. William Optics includes the ever-popular Canon EOS adapter ring with the Star 71, but other adapters are widely available for your particular camera set-up.

The William Optics Star71 comes with a pair of mounting rings and a Dual Side dovetail. A soft carry case is available optionally, as is a specialized 1.25” diagonal for visual use. Please note that a standard 1.25” diagonal will not work with this telescope, and neither will a 2” diagonal as they will not come to focus.

William Optics WO-Star 71 Specifications

  • Aperture: 71 mm
  • Focal Ratio: f/4.9
  • Focal Length: 350.2 mm
  • Objective Type: 4 elements in 3 groups - patented 2-1-1 Configuration
  • Lens ShadeRetractable
  • Focuser: 2.5” Dual Speed Rack & Pinion
  • Focuser Drawtube travel: 1.38" / 35mm
  • Image Circle: 45 mm
  • Type of Mount: Mounting rings with Dual Side dovetail
  • OTA Tube Weight: 4.5 lb / 2.05 kg
  • Tube Weight with Rings & Dovetail: 5.3 lb / 2.4 kg


Important Note Regarding William Optics
Apochromatic Lenses


All of the APO objective lenses in William Optics refractors are double-tested and inspected before they ship from the factory and will be free of coma and astigmatism. However, due to the mechanized coating process utilized on all lens surfaces you may see cosmetic imperfections in the surface that do not affect its performance in any way. The dimensions of these superficial scratches and points shall not exceed the following values:

  • Scratches - Maximum Width: 0.025 mm
  • Scratches - Maximum Length: 1/4 of total lens diameter
  • Scratches - Maximum Quantity: Three
  • Dots or Spot Points - Maximum Diameter: 0.4 mm
  • Dots or Spot Points - Maximum Quantity: Three
  • Accumulation of Defects - Limited Area: 0.8mm^2
  • Accumulation of Defects - Total Area: 5.8mm^2