William Optics Ultra-Cat 131 (T-C-131BR)

William Optics Ultra-Cat 131 The William Optics Ultra-Cat 131 is the flagship of the Ultra-Cat series, representing the pinnacle of wide-field astrophotography performance. Built around a large-aperture 131mm apochromatic optical system and an advanced 5-element Petzval design, it delivers extraordinary light-gathering power, exceptional color correction, and razor-sharp stars across an expansive, flat image circle. Designed for serious astrophotographers and observatories alike, the Ultra-Cat 131 combines a fast focal ratio with uncompromising optical precision, enabling stunning deep-sky detail, rich contrast, and immersive wide-field compositions. Its premium mechanical construction, thermal stability, and flagship-level engineering set a new benchmark for large-format astrophotography systems. 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 Xterminator 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. Powering the Grandest Deep-Sky Visions The Ultra-Cat 131 stands as the flagship of the series, redefining wide-field imaging performance. Built on an uncompromising 5-element Petzval optical system, it delivers exceptional flat-field precision, color fidelity, and light-gathering power. Purpose-engineered for advanced astrophotographers, the Ultra-Cat 131 turns ambitious deep-sky visions into true-to-life celestial images with confidence and control. Advanced Petzval Researched and developed by WO, the innovative 5-element Petzval design redefines telescope optics. This advanced system achieves a flawless spot diagram across a medium-format image circle. Extra-low Dispersion (ED) glasses Contains 2 Super ED, 1 ED glasses and lanthanum lenses with advanced fully multi-coated, delivering sharp, vibrant images with true-to-life colors, significantly reducing chromatic aberration. Needs NO Flattener The Petzval design inherently flattens the field, eliminating the need for an external field flattener. Technical Specifications 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 (STX-R) 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 11.3 kg / 24.91 lbs Total Weight 13.97 kg / 30.8 lbs In the Box Main TubeBahtinov CapM48, M54, M68 Camera Adapter Losmandy Plate Mounting Ring & Handle bar Soft Carry Case Warranty & Manual Manual William Optics 2-Year Warranty