Manufacturer: William Optics
Product number: GT81WIFD-R

EUR 2.059,00


incl. 19 % VAT (DE)  
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  • On stock
  • Only 1 pcs left in stock





rating: 5.0 of 5
  • Details..
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  • In the box..
William Optics Gran Tourismo GT81 WIFD Triplet Apochromat with internal Focusing
Introducing the WILLIAM OPTICS Internal Focus Design (WIFD) Apochromatic Series

This innovative and revolutionary design combines a precision (patented) internal focusing mechanism with the highest quality optics available, providing the ultimate apochromatic refractor for astrophotography. Designed from the ground up with the ability to handle 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.

WIFD Focuser Design

The internal focuser design includes the patented WO center focuser with precise internal sliding of fixed optics to prevent image shift. The integrated position viewing window on the focuser provides instant verification of the graduated numerical display. The smooth rack and pinion design is incorporated into the focuser to provide super fine adjustability for critical focus. The internal movement of the optical elements is protected from the elements and can´t come out of alignment. The redistribution of weight allows for better balance during imaging sessions.

Scalable Design Priciple

The WIFD series will allow for many sizes and is not limited to smaller refractors. Additional optical designs are possible to meet various photographic requirements enhancing the line to include a number of apertures and fast focal ratios.

Inspired by the tremendous success of the WO CAT series of astrographs, William Optics has advanced the capabilities of astrophotography to the next level with this "no weight limit on photo accessories" design. The solid tube, where accessories are attached, has a rigid design and will not flex or exhibit any change in the optical path regardless of the weight of the camera and filter wheel attached to it.

Cat Design

Improved "CAT" design ring tubes and dovetail base are lighter while remaining equally rigid. The design allows for better balance with heavy accessories and has integral placement of the focuser knobs, providing easy access to focusing during imaging. Included is the popular WO Saddle Bar Handle, critical for rigid guidescope mounting and autoguiding performance.

Super Smooth Field Rotator

The field rotator design features smooth camera rotation with markings for degrees and a locking thumbscrew to prevent accidental camera movement, also a electric rotator will be available in near future.
Objective type:Triplet apochromatic objective
Apo element material:FPL53
Strehl Ratio:0.95+
Aperture:81 mm
Focal length:478 mm
f/ ratio:f/5.9
Focuser:WIFD, compatible with EAF
Camera side adaptation:M92x1 female, M63x1 female
Color:Red
Camera format:Full Frame, DSLR, Mirrorless, CMOS, CCD
Test report:Included
Weight:4.5 kg
William Optics Gran Turismo Apo
Dust protection caps
Carrying handle
Dovetail bar
Test report
Carrying bag



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Reviews

Written by Bert Wilde
on 2023-07-05

"Wow! It delivers. Solid built, focuses spot-on with zero to none backlash/hysteresis. Great results."