Ultra-Cat 131 · 30th Anniversary Limited Edition
The Ultra-Cat 131 · 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 30 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 131 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 Design
Eliminates field curvature, providing sharp, flat-field images without requiring additional flatteners.
60mm Superior Image Circle
Fully supports full-frame and medium-format cameras for wide-field and detailed astrophotography, outperforming standard 106mm telescopes.
F/4.9 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.
Personalized Laser Engraving
Free customization for direct purchases, adding a personal touch to your telescope.
- Limited 30 sets
- Coming Soon - shipping begins early March
![[Bundle] Ultra-Cat 131 · 30th Anniversary Edition & ZWO AM7 Full Package](http://williamoptics.com/cdn/shop/files/PM90_UC131-30th-1.jpg?v=1770705989&width=2400)
![[Bundle] Ultra-Cat 131 · 30th Anniversary Edition & ZWO AM7 Full Package](http://williamoptics.com/cdn/shop/files/PM90_UC131-30th-2.jpg?v=1770705989&width=3066)
- Lens Type
- 5-Element Advanced Petzval
- Lens Elements
- Super ED Glass x2 ED Glass x1 Lanthanum Glass x1 X-Element x1
- Focal Length
- 648 mm
- Diameter
- 131 mm
- Focal Ratio
- f/4.9
- Image Circle
- 60 mm
- Focuser
- WIFD R&P Focuser Compatible with EAF
- Focuser Travel
- 0-20 mm
- Adapter Included
- Sensor Tilt Xterminator Rotator M68, M54, M48 Camera Adapters
- Optional Flattener
- No Flattener Required
- T-Mount Support
- Canon EF, RF Nikon F, Z Sony E Pentax K MFT (M4/3) FUJI X
- Camera Format
- Medium Format Full Frame APS-C M4/3
- Dovetail Type
- Losmandy
- Tube Length
- 650 mm - 785.5 mm
- OTA Weight
- 9.95 kg / 21.94 lbs
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Three Decades of Vision, Inspiring Generations to Come.
Celebrating 30 years of William Optics craftsmanship, the Ultra-Cat 131 brings the acclaimed five-element Petzval design into a commemorative edition. Compact yet powerful, it delivers premium optical performance with a special anniversary finish, engraved emblem, and serialized marking—a telescope that honors the past and inspires the future.
Limited 30 Units
Individually numbered to underscore its exclusivity as a commemorative edition.
Symbolic Laser Engraving
A unique design of a cat embracing the number “30,” honoring the legacy of the Cat series.
Founder’s Signature
Personally hand-signed by William Yang on the lens cover, every telescope is a unique collector’s piece.
Commemorative Certificate
Accompanied by an official 30th Anniversary certificate to mark its special place in William Optics history.