The Ultra-Cat 76 · 30th Anniversary Edition is a commemorative refractor celebrating three decades of William Optics craftsmanship and innovation. Built upon the acclaimed five-element advanced Petzval optical design, this limited edition of 100 units worldwide combines uncompromising astrophotography performance with a symbolic anniversary finish.

Featuring a unique laser-engraved emblem of a cat embracing “30” ,personally hand-signed by founder William Yang on the lens cover, and accompanied by a 30th Anniversary Certificate, the Ultra-Cat 76 is not only a professional imaging instrument but also a collector’s piece that honors the Cat series legacy.

Key Features:

Advanced 5-Element Petzval Optics
Eliminates field curvature, ensuring sharp, edge-to-edge stars without additional flatteners.

50mm Large Image Circle
Fully supports Full Frame cameras, APS-C and M4/3 sensors for optimal performance. Compatible with Medium Format.

Fast f/4.8 Optics
Superior light-gathering capability, enabling deep-sky imaging with shorter exposure times.

WIFD (William’s Internal Focuser Design)
Patented internal rack-and-pinion focuser ensures stable and precise focusing.
No vignetting or balance issues — ideal for astrophotography.
Compatible with EAF (Electronic Automatic Focuser) for precision focus control.

Sensor Tilt Xterminator (STX) & Rotator
Integrated tilt adjuster eliminates sensor misalignment, ensuring uniform image sharpness.

No Flattener Required
The optical design naturally corrects field curvature, simplifying setup.

Anti-Shrink Lens Cell Technology
Reduces thermal expansion effects, maintaining perfect optical alignment in any climate.

Patented Bahtinov Mask for Focusing
Built-in focusing aid ensures pinpoint star sharpness with ease.

Premium Build & Ergonomic Design
Lightweight yet robust (4.31 kg / 9.5 lbs) construction with a sleek anodized finish.
Patented handle bar design for enhanced portability and ease of use.

Versatile Camera Compatibility
Supports Canon EF, RF, Nikon F,Z, Sony E, Pentax K, MFT, and FUJI X mounts.

Ultra Cat Series

Ultra-Cat 76 · 30th Anniversary Limited Edition