William Optics WIFD Ultra-Cat 76 f/4.8 APO 

The William Optics Ultra-Cat 76 is a powerful astrograph designed for capturing stunning deep-space images. Its fast f/4.8 focal ratio, achieved with a 76 mm aperture and 365 mm focal length, makes it ideal for wide-field astrophotography. Built with 5 precision-crafted lens elements, this Petzval refractor delivers sharp, well-corrected images across the entire field, eliminating the need for a field flattener or backspace adjustments.

Its large 50 mm image circle easily accommodates medium-format and full-frame cameras, while the William Optics Internal Focus Design (WIFD) ensures smooth and stable focusing. For added convenience, it’s also compatible with an optional electronic autofocuser, making it a versatile and efficient tool for astrophotographers seeking high-quality results.

Advanced 5-Element Petzval Design
Eliminates field curvature, providing sharp, flat-field images without requiring additional flatteners.

F/4.8 Fast Optics
Offers exceptional light-gathering capability for vibrant deep-sky photography.

WIFD (William’s Internal Focuser Design)
Patented internal focuser ensures precise, stable, and hassle-free imaging, avoiding balance issues and eliminating vignetting.

Anti-Shrink Lens Cell Technology
Minimizes thermal expansion and contraction, maintaining perfect optical alignment in any environment.

Sensor Tilt Corrector
Integrated and patented design eliminates distortion, optimizing sharpness and detail for professional-level results.

Built-In Patented Bahtinov Mask
Simplifies focusing for pinpoint precision, a feature that sets it apart from competitors.

Patented Handle Bar Design
Combines ergonomic usability with enhanced portability.

STX-A Smarter, More Efficient Tilt Adjustment System

The Ultra-Cat 76 comes equipped with William Optics' new Sensor Tilt Xterminator (STX) technology, ensuring precise sensor alignment and eliminating tilt issues for optimal astrophotography results.

The STX builds upon the foundation of traditional sensor tilt adjusters, offering a streamlined and intuitive design that eliminates the need for cumbersome disassembly. Unlike conventional systems that require camera removal for tilt correction, the STX allows adjustments to be made directly from the side of the assembly, significantly reducing setup time and enhancing ease of use.

By refining the original 4 pull-in and 8 push-out screw configuration into a more efficient 4 push-out and 4 locked screw system, the STX enables precise and controlled adjustments. Operating like a seesaw mechanism, the system allows for effortless corrections—simply loosen one screw and tighten the opposite diagonal screw to achieve fine tilt alignment. This ensures that astrophotographers can make on-the-fly refinements without disrupting their imaging workflow, maintaining pinpoint star performance across the entire frame.

Diagram Report

Technical Specifications

In the Box

• Ultra-Cat 76 OTA

• Sensor Tilt Xterminator

• Rotator

• M54 Camera Adapter

• M48 Camera Adapter

Warranty & Manual

William Optics 2-year Warranty