The Williams Optics WIFD GT81 APO is the first offering from William Optics featuring a new Internal Focus Design (WIFD) Apochromatic Series of telescopes.
As the William Optics team notes, “The Internal Focus Design (WIFD) Apochromatic Series offers an innovative and revolutionary design which 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 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.”
The Williams Optics WIFD GT81 APO’s new internal focuser offers 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 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 focusers redistribution of weight allows for better balance during imaging sessions.
The William Optics team also notes, “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.”
The Williams Optics WIFD GT81 APO incorporates the WO “CAT” design ring tubes and dovetail base which are now lighter than before while remaining equally rigid. This new 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 WO Saddle Bar Handle, which facilitates rigid guidescope mounting and autoguiding performance.
The telescope’s field rotator design features smooth camera rotation with markings for degrees and a locking thumbscrew to prevent accidental camera movement. The company notes it has future plans to offer a new electric rotator.
The Williams Optics WIFD GT81 APO specifications include:
– Lens Type: Triplet Apochromatic Prime Lens
– Focal Length: 478mm
– Diameter: 81mm
– F/ Ratio: f/5.9
– Optional Flattener: WO FLAT6AIII 0.8x FLAT68III 1.0X (Requires WIFD Extension Adapter)
– Focuser: WIFD, Compatible with EAF
– Color: Red
– Lens Material: FPL-53 ED
– Strehl Ratio: 0.95+
– Camera Format: Full Frame DSLR Mirrorless CMOS CCD
– Test Report: Included
– T-Mounts Supported; Canon EF, RF; Nikon F, Z; Sony E; Pentax K; Micro Four Thirds (M4/3); FUJI X
– OTA Weight: 7.3lbs (3.3kg)
– Total Weight: 9.9lbs (4.5kgs)
– Tube Length (Retracted): 420mm
– Tube Length (Extended): 500mm
You can learn more about the Williams Optics WIFD GT81 APO here.
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