William Optics GT81 WIFD Apochromatic Refractor

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William Optics 32mm Slide-base Uniguide Scope Add to Basket:----------Colour:  Gold:  + £99.00Colour:  Red:  + £99.00Colour:  Space Grey:  + £99.00

Steve Ringwood writing for Astronomy Now Magazine

"The 81 mm, f/5.9 telescope from the stable of William Optics has been a long favourite with visual and imaging astronomers thanks to its triplet apochromatic prime lens, its FPL-53 glass and a Strehl ratio of better than 0.95, all ensuring great performance.

Now this telescope has got even better in the form of the Gran Turismo GT81 WIFD (William Optics Internal Focus Design). In order to avoid the changing gravitational dynamics and stress consequences of having the external focus attachment moving back and forth, focusing has been moved completely in-house, so to speak. 

Focus is now imparted by a floating system entirely incorporated within the tube. This not only avoids image shift imparted by the engineering constraints of an external focusing tube, but also removes the consequent changes in the light path that can introduce vignetting. The telescope is therefore able to provide a rich, un-vignetted field for full frame DSLR, CMOS and CCD imaging devices.

The addition of extra strength at the instrument's end of the tube means that the telescope is able to handle a significant imaging payload - with almost no weight limit." 

About this product

William Optics GT81 WIFD Apochromatic Refractor

This innovative design combines a precision (patented) internal focusing mechanism with premium apochromatic optics.

Designed to handle the newest generation of large, heavy, high-resolution cooled cameras.

The focuser is integrated inside the main tube assembly, so no focuser drawtube movement is visible from the outside.

Enjoy the benefits of a traditional two-speed fine focuser without the limitations found in conventional rear-mounted focusers. 

Includes a custom-made soft padded case. 

NEW internal focuser.  This new telescope includes the Patented centre focuser with precise internal sliding of fixed optics to prevent image shift. The integrated viewing window on the focuser has a useful graduated numerical display. The smooth rack and pinion mechanism integrated into the focuser enables super-fine focus adjustment. The design's redistribution of weight provides better balance during imaging sessions. Also, the telescope's optics are more protected from the environment and less likely to move out of alignment. 

Scalable Design.  The WIFD series is not limited to smaller refractors. With its inherent benefits, the design can be applied to telescopes with various apertures and fast focal ratios. Other WIFD telescopes are planned. 

Inspired by the success of their CAT series of astrograph telescopes, William Optics have adopted a 'no weight limit on photo accessories' approach to telescope design. The solid tube has a rigid structure, so it does not flex or exhibit any change in the optical path, regardless of the weight of the camera and filter wheel attached.

Improved “CAT” design.  Tube-rings and the dovetail base are made lighter, without sacrificing rigidity. The design enables better balance with heavy accessories and has integral placement of the focuser knobs for easy access during imaging. William Optics' Saddle Bar Handle is included 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. A new optional Electric Rotator will be available shortly.

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