William Optics GT81 f/5.9 APO Triplet Refractor w/ 0.8x Reducer- Discontinued

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William Optics GT81 f/5.9 APO Triplet Refractor w/ 0.8x Reducer- Discontinued   Discontinued
Item # WO-A-F81GT-AP
  • With an f/5.9 focal ratio, this William Optics GT81 APO Triplet Refractor is perfect for astrophotography.
  • All lens surfaces are fully multi-coated with a special super-high transmission coating.
  • This William Optics GT81 APO Triplet Refractor includes the William Optics FLAT6A Field Flatter that will reduce the GT81's focal length by a factor of 0.8x.
  • Also comes with an L-bracket with night glowing carry handle and finderscope guide rings.
  • Fully rotatable 2.0" dual-speed rack & pinion focuser with 1:10 micro focusing.


William Optics GT81 APO Triplet Refractor Telescope

Among available apochromatic refractors, the amazing William Optics 81mm Triplet APO Refractor is one of the best. Although this CNC-machined optical tube has a spotless, gloss white finish, its benefits go beyond its outside appearance. The GT81 uses first-rate FPL-53 extra-low dispersion glass to lessen any secondary spectrum to an extent many people would find astonishing.

William Optics GT81 APO Triplet Refractor Telescope Features...

  • Triplet air-spaced objective (FPL-53) in adaptable CNC machined ultra high precision lens cell
  • Superior sharpness
  • Exceptional color correction
  • All lens surfaces are fully multi-coated with a special super-high transmission coating (STM coating)
  • f/5.9 lens is optimal for astro-imaging
  • Includes 2" - 1.25" adapter
  • Brass compression rings that will consistently stay blemish-free
  • Glow-in-the-dark carry handle
  • William Optics 2-Year Warranty

2.0" Rack & Pinion Focuser

  • Super smooth 2.0" Rack & Pinion focuser that rotates 360º and has 1:10 dual speed microfocusing. Complete lack of image shifting makes astrophotography much more pleasant
  • Two locking screws on angled positions are included for when a heavy load is employed
  • Large aluminum knobs make focusing a simple task, even for those wearing gloves

William Optics Product Number: A-F81GT-AP

Images depict some accessories not included with this package.
Additional Information

Additional Information

Manufacturer William Optics
Telescope Series William Optics GT
Optical Design Refractor - Apochromatic
Mount Type None - Optical Tube Only
Warranty 2 Year Warranty
Telescope Aperture 3.18"
Telescope Focal Length 478mm
Telescope Focal Ratio f/5.9
Optical Tube Outer Diameter 90mm
Length of Optical Tube 440mm retracted, 484mm extended
Tube Color or Finish Gloss White
Dew Shield Included? Yes
Limiting Stellar Magnitude 12.2
Finder Included None
Focuser Size 2"
Focuser Style Rack & Pinion
Focusing Speeds Two-Speed
Included Items

Included Items

  • William Optics GT81 Triplet APO Refractor Telescope
  • Flat-6A 0.8x Reducer/ Flattener
  • 2.0" Rack & Pinion Dual Speed Focuser
  • Retractable Lens Shade
  • 2"-1.25" Adapter
  • L-Bracket with Carry Handle
Questions & Answers

Product Questions

What would be the DSLR back focus difference between SONY SLTA55 and Canon EOS ? Is there a different adapter available for SONY Alpha models A-Mount ?
So does the reducer bring it to F4.7, or is the stated F5.9 with the reducer
Hi do the gold attached tube rings come with this scope.I ask as it mentions not everything shown comes in package.thanks 
Q1: Does it require an 2" extension tube to be put into the focuser to get into focus with DSLR? Q2: the flattener has a T-Ring for Canon which is fitted via T2 onto the flattener,the flattener has 2" tube to be inserted into 2" focuser, is that correct?
Is the flatterer compatible with NIKON cameras and its T-Rings??
What is the size of the included guide scope rings?
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