William Optics GT-81 - 20th Anniversary Limited Edition - Checked & Tuned



Available - Delivery 20-30 working days.

Model:  wo-gt-81_anniversary_ota
Part Number:  A-F81GT-VP20A
Brand:  William Optics

Special Bundle Price - Save £44!

Buy a William Optics GT-81 Triplet Refractor and Reducer/Flattener 6 together for 1,299

Simply add both items to your basket to automatically receive the discount.


  • Telescope OTA
  • Vixen compatible L-Bracket
  • Carry Handle
  • Guiding / Finder rings
  • 2" Extension Tube
  • 2" to 1.25" Adapter
  • Soft Carry Bag

ES Reid Checked Telescope

Es Reid is highly regarded in the optical industry so to ensure our refractors perform at their very best we send them to him for checking and, if necessary, tuning on his optical bench. 

Inevitably some telescopes require more time on the bench than others but we average the costs so this extra layer of quality control adds only £75 to the purchase price. 

A small price to pay for peace of mind.

You can order your telescope with confidence knowing it will have well figured optics, negligible false colour and spherical aberration, and no astigmatism (the bane of any optical system!). Star shapes will be round, not triangular, oval or egg-shaped!

You know it makes sense :-) 

Limited 20th Anniversary Edition - Checked & tuned, for details see here

The William Optics GT-81 APO Triplet refractor features a 3-element f/5.9 objective with an Ohara FPL-53 extra-low-dispersion glass element for optimum colour correction and a new upgraded dual-speed 2-inch Crayford V-power focuser with a smoother action and no image shifting with a capacity of up to 6.8kg (15lb). 

The Hotech SCA Field Flattener is an excellent match for this telescope.  

The William Optics 0.8x focal reducer is also available to reduce the focal-ratio to a fast f4.72. 

An excellent choice for astrophotography!

Includes mounting bracket, carry handle, finder/guider rings and high quality soft carry case.


    Optically Unbeatable

  • Triplet air-spaced objective (FPL-53) in adjustable CNC machined ultra high precision lens cell.
  • Extremely sharp.
  • Excellent color correction.
  • Each lens is Fully Multi-Coated with a special super-high transmission coating (STM Coating) on all surfaces.
  • This F/5.9 lens is ideal for astrophotography.

    2.0" Crayford V-power Focuser

  • New ultra smooth 2" Crayford V-power edition focuser with 1:10 dual speed: a treat to use during astrophotography. No image shifting (capacity 6.8kg / 15lb)!
  • Comes with two locking screws on angled positions for heavy load applications.
  • Chromed, soft thumbscrews, easy to use even with gloves on.

    Patented Design

  • Stainless steel reinforcement inserts on both sides and on the back to allow heavy loading without problems.
  • Diamond-coated drive system: very smooth, no lateral movement or tilting. 
  • Graduated scale for precise camera alignment.

    Simply Beautiful Finish

  • Pure William Optics quality fit and finish: powder-painted white CNC-machined Aluminium tube, gold trim finish, retractable dewshield, dewshield cap.
  • Top quality anodising.
  • Very compact for carrying on flights.

    Attention to Details

  • 2" & 1.25" adapter included in the price.
  • Anti-marring brass compression rings.
  • Carry handle with V-shape night glowing illuminator.
  • 90mm mounting rings are optional.
  • Though you will never need it, you have a 2-year warranty from WO, and the certainty that we will be there to assist you even beyond that, if you need!

Product Videos

Product Specifications

Aperture 81mm
Focal Ratio F/5.9
Focal Length 478mm
Resolving Power 1.43"
Limiting Magnitude 12.2
Objective Type Three element with FPL-53 Air Spaced, Fully Multi-Coated,STM coatings
Lens Shade Retractable
 V-power Focuser 45mm drawtube, 1:10 fine focus


1.25" Adapter
Field Stops Knife-Edge Baffles
L-type Mount Bracket
Tube Diameter 90mm
Tube Length (440 mm) Fully Retracted


(484 mm) Fully Extended
Tube Weight 8 lbs.( 3.7kg)

William Optics GT-81 - 20th Anniversary Limited Edition - Checked & Tuned Questions & Answers

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Customer Services Report
February 2017 / View Older
Positive Feedback read all 4120 comments
Enquiries Responded to within 6 working hours
Orders Completed within 2 working days