William Optics GT81 Grand Turismo Refractor with WIFD Focuser - Red - T-GT-81RD-WIFD

The William Optics GT81 Triplet Refractor has a focal length of 478 mm and an f/ratio of f/5.9.  FPL-53 glass is used in the optical system to reduce chromatic aberration and produce sharp, high contrast images, whether using the GT81 for observing or astrophotography.  

This GT71 WIFD model is white with red trim; it is also available in space gray or gold at the same price.  We may show other colors if the image itself is helpful.  Just remember that you will get a white/red telescope, regardless of the colors you see on this page.  Thanks.

WIFD Technology

 The William Optics Internal Focus Design, or WIFD, is an innovative and revolutionary design that combines a precision internal focusing mechanism with high quality optics, providing the ultimate apochromatic refractor for astrophotography.

Designed from the ground up with the ability to handle the newest generation of large, heavy, high-resolution cooled cameras, the rock-solid optical tube assembly is uncompromised in quality. The movement of the focuser is integrated inside the main tube assembly, so there are no movements of a focuser drawtube visible from the outside.  The user can enjoy the benefits of a traditional two speed fine focuser, while not worrying about limitations typically found in traditional rear mounted focusers. 

Included Accessories

• GT81 f/5.9 Tube Assembly - White with Red Trim
  
• Dust Cover with Bahtinov Mask
  
• 120 mm Saddle Handle Bar
  
• Camera Angle Rotator
  
• M92 to M63 Adapter
  
• 210 Vixen-Style Dovetail Plate
  
• Soft Carry Case
  
• ZYGO Test Report
  

Specifications

• Lens Design:  APO Triplet with 1 FPL-53 Element
  
• Aperture:  81 mm
  
• Focal Length:  478 mm
  
• Focal Ratio:  f.5.9
  
• Focuser:  WIFD
  
• Image Circle:  45 mm (Full Frame)
  
• Retracted Length:  421 mm
  
• Extended Length:  502 mm
  
• Dew Shield Circumference:  382 mm
  
• Dew Shield Diameter:  121 mm
  
• Weight of OTA Only:  3.58kg
  
• Weight of OTA with Ring, Dovetail & Saddle:  4.565kg
  
• Color:  White with Red Trim
  
• Strehl Ratio:  0.95+
  
• Test Report:  Included
  
• Optional Flattener:  FLAT6AIII 0.8X or FLAT68III 1X, which requires an WIFD Extension Adapter