William Optics

• Very high quality optics
• Universal use (as a guider or astrophotographic telescope)
• Compatible with Flattener 61
• Usable as guider with 360mm focal length for primary optics with focal lengths between 700mm and 1200mm

This Reducer Flattener is designed to take the optical performance of your telescope to a new level. With a reduction factor of X0.8 and an outstanding flattener function, it minimizes distortions and aberrations that can occur during observation and photography.

The 0.8x Flattener corrector from William Optics is optimized for full-frame format and suitable for all apos from 102mm aperture with large extensions.

• Connection thread on the telescope side M92x1 - adapters to M68 or M54 are optionally available
• The distance is precisely adjustable, so the corrector can be individually
• optimized to the refractor for best possible stars
• Triplet design with Ohara glass (Japan)
• M48x0.75 camera mount with possibility to screw in 2" filter

William offers with the RedCat 71 WIFD astrograph a very well corrected telescope for astrophotography up to full frame format.

• Aperture 71 mm / Focal length 350 mm / Focal ratio f/4.9
• Petzval design with chromatic aberration free FPL53 objective (4 elements in 3 groups)
• Very well corrected and illuminated image field up to full frame format - the corrector is built in - no more adapter battle necessary
• Camera connection via M48 male thread (suitable adapters are available) - working distance 55 mm
• 360° rotation of the camera for the right display window
• Focusing via internal focusing (William Internal Focus Design - WIFD) as with telephoto lenses
• Tilting option for individual adjustment of the camera sensor to the telescope
• Flexible dovetail bar at the base (long version), suitable for Vixen style and Arca-Swiss saddle plates, in addition with 1/4" female photo tripod thread
• Nylon carrying bag and Bahtinov mask for astrophotography are included in delivery
• WIFD R&P focuser - copatible with EAF

The William Optics GT 81 apo stands for optimal chromatic correction and best possible contrast - a powerful travel telescope for observation and photography.

• Aperture 81 mm
• Focal length 480 mm
• Focal ratio f/5.9
• Multicoated, air-spaced FPL53 triplet lens
• 2.5" RAP focuser with M63x1 connection thread, as well as 2" and 1.25"
• Multifunction handle with holder for guide scopes
• Bahtinov mask integrated
• Variable carrier bag
• Vixen/EQ5 style dovetail bar

Key Features:

F/3.2 Ultra-Fast Optics
Captures deep-sky objects with unparalleled efficiency, utilizing the fastest optical system in William Optics history to maximize photon collection and shorten exposure tracks.

Advanced 7-Element Petzval Design
Provides a naturally flat image field without requiring an additional field flattener, delivering sharp stars and clean detail across a wide imaging area.

43.2mm Full-Frame Image Circle
Supports full-frame, APS-C, and M4/3 camera systems, giving astrophotographers total freedom for wide-field composition and high-resolution deep-sky imaging.

WIFD (William Optics Internal Focuser Design)
The patented internal focusing system keeps the focusing mechanism centered inside the telescope, improving balance and helping avoid rear drawtube-related flexure or vignetting.

Sensor Tilt Xterminator (STX-R)
Features a heavy-duty rear tilt and rotation interface designed to support modern imaging setups, reducing the chance of rear-end sag while retaining convenient sensor-squaring capability.

Anti-Shrink Lens Cell Technology
Helps maintain stable optical alignment under changing temperatures by minimizing the effects of material expansion and contraction around the lens cell.

Built-In Patented Bahtinov Mask
Integrated into the front cap for quick and accurate focusing, making precise star focus easier in the field.

Patented Handle Bar Design
Improves handling, portability, and accessory mounting while maintaining the clean mechanical layout of the Mighty Cat platform.