Focus Scientific

William Optics Gran Turismo 81mm f/5.9 Apochromat Refractor OTA (Red)

The new GT81 three-element super APO offer superb quality for imaging and visual use at an affordable price. The pristine white finish and the elegant red trim embodies more than just good looks.

Features

  • 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
  • The F/5.9 objective is ideal for deep-sky astrophotography
  • 2.5” R&P Ultra robust focuser with 1:10 dual speed: a treat to use during astrophotography, with no image shift and no "Crayford slip"
  • Innovative Bahtinov Mask Cover (Patented) & New Dualside Dovetail Plate (DSD 210) included
  • Pure William Optics quality fit and finish: powder-painted white CNC-machined aluminum tube, red trim finish, retractable dewshield, dewshield cap
  • Top quality anodizing
  • Very compact for carrying on flights
  • 2" & 1.25" adapter included in the price
  • Anti-marring brass compression rings
  • 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!
  • Retracted Length: 390mm (15.4")
  • Tube with Rings and Dovetail Weight: 3.84kg (8.5 lbs)

Standard Package Includes

  • Mounting Rings
  • Guiding Rings
  • New Dualside Dovetail Plate (DSD 210)
  • 2.5” R&P Focuser
  • Innovative Bahtinov Mask Cover (Patented)
  • Soft Carry Case
  • Two-year, no fuss warranty and constant customer service!

Specifications

  • Aperture: 81mm (3.1")
  • Focal Ratio: F/5.9
  • Focal Length: 480 mm
  • Objective Type: Synthetic Flourite FPL 53 Triplet, Air Spaced, APO
  • Fully Multi-Coated, STM coating
  • Image Circle Diameter: 44mm
  • Lens Shade: Retractable
  • Focuser: 2.5" R&P Focuser with 1:10 Dual Speed micro focuser
  • Focuser Travel: 93mm, graduated in millimeters
  • Dial Type Thermometer Built Into Focuser
  • Bhatinov Mask Cover for Critical Focus
  • 1.25" and 2" Adapter: Compression Rings
  • New Dualside Dovetail Plate (DSD 210)
  • Field Stops: Baffles for Stray Light Suppression
  • Retracted Length: 390mm (15.4")
  • Tube with Rings and Dovetail Weight: 3.84kg (8.5 lbs)
  • Two year warranty