The Glorious Cat, Engineered Beyond.
Highlights
Ultra-Sharp 5-Element Petzval Optics
Redefines optical performance with a refined 5-element Petzval design, ensuring crisp, high-contrast views with outstanding color correction across the entire field.
Ultra-Wide Imaging Compatibility
Provides seamless compatibility with full-frame/medium format sensors, delivering expansive, high-quality astrophotography with exceptional detail.
Ultra-Friendly Exclusive Design
Equipped with the WIFD focuser and STX mechanism, offering smooth focusing and simplified sensor alignment, making astrophotography more efficient and user-friendly.
5 Elements
Advanced Petzval
APO Design
Extra-low Dispersion (ED) glasses
Deliver 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.
High-precision polishing
Our lenses undergo high-precision polishing, setting a standard of excellence that surpasses industry norms, ensuring optimal performance in all conditions.
Sharp And Quick Aperture
| Ultra-Cat 76 | Cat 91 |
|---|---|
| f/4.8 | f/4.9 |
| Ultra-Cat 108 | |
| f/4.8 |
Innovation debuts
Sensor Tilt Xterminator
The UltraCats are equipped with the Sensor Tilt Xterminator (STX), allowing quick side-access tilt adjustments without removing the camera. The simplified mechanism requires adjusting only 4 knobs, operating like a seesaw, ensures easy, accurate alignment. (STX not included in Cat-91.)
WIFD Focuser
The William Optics Internal Focus Design (WIFD) relocates the focuser to the center of the telescope.
This design effectively eliminates tube tilt issues caused by the weight of cameras and accessories. By ensuring a balanced structure and precise internal sliding of fixed optics, the WIFD system delivers stable, clear observations while maintaining a dust-free and easy-to-maintain focuser environment.
Learn more
Compatible with Electronic Motorized Devices
Hassle Free Installation
( No Mounting Bracket Kit required )
Fast and accurate focusing
Integrated Bahtinov mask in dew shield cap (Patent number: US 10,564,409 B2) ensures precise focusing. Made of high-definition and stable optical PMMA. Enhances astrophotography experience with quick and accurate adjustments.
Ultra-Cat 76
Image Circle: 50mm
- Full-Frame ( 36×24 mm )
- APS-C ( 23.5×15.6 mm )
Cat 91
Image Circle: 55mm
- Medium-Format ( 44×33 mm )
- Full-Frame ( 36×24 mm )
- APS-C ( 23.5×15.6 mm )
Ultra-Cat 108
Image Circle: 60mm
- Medium-Format ( 44×33 mm )
- Full-Frame ( 36×24 mm )
- APS-C ( 23.5×15.6 mm )
Which Cat is right for you?
Cat 91 $2,798.00 View |
Ultra-Cat 108 $3,798.00 View |
Ultra-Cat 76 $1,888.00 View |
|
|---|---|---|---|
| Lens Type | 5-Element Advanced Petzval | 5-Element Advanced Petzval | 5-Element Advanced Petzval |
| Focal Length | 448 mm | 518 mm | 365 mm |
| Diameter | 91 mm | 108 mm | 76 mm |
| Aperture | f/4.9 | f/4.8 | f/4.8 |
| Image circle | 55 mm | 60 mm | 50 mm |
| Focuser |
WIFD R&P Focuser
Compatible with EAF |
WIFD R&P Focuser
Compatible with EAF |
WIFD R&P Focuser
Compatible with EAF |