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William Optics ZenithStar 81 APO Doublet Refractor - Blue - A-Z81BU

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William Optics Blue ZenithStar 81 APO Doublet Refractor

This 81mm ZenithStar APO refractor is a great addition to the ranks of telescopes that are devoted to providing fantastic astro-images through high-quality optics and chromatic aberration correction. Not only does this telescope have good optics, but it's also easy to use and very portable!

Equipped with FPL-53 glass and being apochromatic, this scope gives beautiful colors and provides clear details. This is a great telescope that has an image circle that works well with full frame camera with APS-C, which minimizes vignetting and image shifting.

Included Accessories

Mounting Rings

These mounting rings are great quality rings that will assist users when mounting the telescope to the mount. The rings are strong enough to safely hold the OTA in place and come in the color of choice so they match the telescope.

CNC Carry Handle Bar

This CNC machined carry handle bar is a new design as of 2019. The beautiful bar will make traveling and moving this portable OTA a breeze. It also comes in the same color as the desired OTA accents. It also gives users the ability to connect a guide scope (not included) directly to the handle. The saddle handle accepts Synta-style dovetails.

2.5" Rack & Pinion Focuser

This focuser from William Optics is a fantastic dual speed focuser with tension screws that virtually ensures the focus will keep, even as the telescope tracks through long exposures.

Dual Sided Dovetail

The included Dual Sided Dovetail (DSD) measures 210mm and has the Vixen design on one side and the Arca Swiss on the other.

Bahtinov Mask

The Innovative Bahtinov Mask cover from William Optics is a great way to hone in the focus of your telescope and are a great addition to any William Optics refracting OTA.


  • Aperture: 81mm
  • Focal Length: 559mm
  • Focal Ratio: f/6.9
  • Focuser: 2.5" Rack & Pinion Dual Speed Focuser
  • Tube Length: 460mm (Fully Retracted) and 560mm (Fully Extended)
  • Total Weight: 3.53kg (7.78 lb)
  • Compatible T Mounts (not included): Canon EF, Nikon F, Sony E, Pentax, Micro four Thirds