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William Optics GT71 71mm f/5.9 Apo Refractor with 2" 0.8x Reducer / Flattener # A-F71GT-AP

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Brand William Optics
Part Number A-F71GT-AP

Product Info

Manufacturer Description

Soft carry bag included!

The stunning new William Optics Gran Turismo 71 Apo is the new jewel of the apochromatic refractor world. The new GT71 features a 3-element objective using high-quality FPL-53 extra-low dispersion glass that reduces any secondary spectrum to an unbelievable degree.

Optically Unbeatable

  • Triplet air-spaced objective (FPL-53) in adjustable CNC machined ultra high precision lens cell.
  • Extremely sharp with 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.

2.5" R&P Focuser

  • Extra-smooth 360 deg. rotatable 2.5" R&P focuser with 1:10 dual speed: a treat to use during astrophotography. No image shifting!
  • Comes with two locking screws on angled positions for heavy load applications.
  • Large aluminum knob with installed thermometer.

Patented Design

  • Stainless steel reinforcement inserts on both sides and on the back to allow heavy loading without problems.
  • Graduated scale for precise camera alignment.

Simply Beautiful Finish

  • quality fit and finish: powder-painted white CNC-machined aluminum tube, gold trim finish, retractable dewshield, dewshield cap.
  • Top quality anodizing.
  • Very compact for carrying on flights.

Specification for ED Lenses

All William Optics refractor objectives are double tested and inspected by WO at their factory. These telescopes are free of coma and astigmatism. Since all individual lens surfaces are machine coated, sometimes you may notice minor visual imperfections which will not compromise the optical performance of the telescope. The dimensions of 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


  • Aperture: 71mm
  • Focal Ratio: f/5.9
  • Focal Length: 420mm
  • Resolving Power: 1.62”
  • Limiting Magnitude: 11.1
  • Objective Type: 3 elements Air-spaced with FPL53 glass
  • Lens Shade: Retractable
  • R&P Focuser: 2.5" 360° Rotating Camera-angle Adjuster, 1:10 fine focus 1.25" Adapter
  • Type of mount: Includes mounting rings and Vixen style dovetail
  • Tube Diameter: 82mm (dew shield tube 92mm)
  • Tube Length: (325 mm) Fully Retracted; (427 mm) Fully Extended
  • Tube Weight: 2.2kg

New from William Optics - slightly modified version of their very popular Flat6 0.8x field flattener/reducer for use with their Z71A telescope. Item includes reducer/flattener assembly, dedicated spacer for Z71A scope, and a Canon EOS T-ring. Weight = 475g.


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Telescope Aperture 2.80" (71mm)
Manufacturer William Optics
Telescope Aperture Up to 80mm
Telescope Series William Optics Zenith Star