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Cyclops Optics

William Optics Zenithstar 81 f/6.9 APO


William Optics Zenithstar 81 f/6.9 APO

Shipping Weight:
8.40 KGS
Accepting order now!
Calculated at checkout

Product Description

Now comes with FREE WO patented Diffraction Spikes Bahtinov Mask Cap

Zenithstar 81 is a greatly versatile and portable refractor telescope for beginners and veterans alike. Designed for both astrophotography and wildlife photography, high power visual observing through the Zenithstar 81 is also hugely satisfying. The image is crisp, sharp and colour aberration free thanks to the use of top quality glass — FPL53, closely matching the legendary fluorite material. The 43mm image circle when Flat6A-III is used covers full frame size sensor nicely. 

Zenithstar 81 Package Includes

  • Z81 Doublet Air-Spaced APO with synthetic fluorite FPL-53 extra low dispersion glass
  • 2.5" Rack & Pinion focuser with 10:1 micro adjustment
  • Mounting Rings
  • Guiding Rings
  • New DualSide Vixen/Arca style dovetail bar (210mm long)
  • 2" to 1.25" adapter with brass compression ring
  • Retractable lens shade
  • FREE WO patented Diffraction Spikes Bahtinov Mask Cap

Z81 Design Highlights

  • 81mm f/6.9 doublet air-spaced objectives APO
  • Use of Japanese made Ohara synthetic fluorite FPL-53 glass material
  • Very sharp image with excellent colour correction
  • Precision optics with fully multi-coated lenses using super-high transmission (STM) coating on all surfaces
  • Designed for astrophotography, wildlife photography & visual observation 

Cyclops Optics' Exclusive Fine Tuning Service

We offer fine tuning service for the telescopes to provide a smoother screws control and grant the telescope a premium quality touch. The fine tune service costs HK$400 (US$50). It's now waived for time-limited period.


Optical system Air-spaced doublets with 1 FPL-53 fluorite element
Aperture 81 mm
Focal length 559 mm
Focal ratio f/6.9
Image circle

Full frame corrected field with Flat6A-III

Resolution 1.83 arcseconds
Limiting magnitude 12.9
Light gathering power 134x
OTA length

460 mm (contracted)
560mm (extended)

Weight 3.5 kg



7 days no question asked return if due to material or workmanship defects

2 years manufacturer's warranty from William Optics

Cyclops Optics Ltd. is an authorised dealer of William Optics' products.

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