See the Ultracat 131 30th Anniversary Limited Edition for earliest availability.

Technical Highlights

The Ultra-Cat 131 is William Optics most advanced astrograph to date, featuring a massive 60mm image circle to support medium-format and full-frame sensors:

• Optics: 5-Element Advanced Petzval (Super ED & Lanthanum glass).

• Aperture: 131mm | Focal Ratio: $f/4.9 | Focal Length: 648mm.

• Focuser: Patented WIFD (Internal Focuser) to eliminate vignetting and tilt.

• Included: Sensor Tilt Xterminator, Rotator, and built-in Bahtinov Mask.