Products in the Same Family
Why Purchase from All-Star Telescope?
Free Expert Support
Whether you are a first timer needing help with setting up or an enthusiast that can't quite make that one thing work, our expert staff are ready to support your needs. With decades of knowledge and first hand experience we've been there and we can help you through it!
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30 Day Return Policy
Buy with confidence knowing that we accept returns up to 30 days after purchase. We want you to have something you will actually use and we are confident that we keep good quality products in our store with No Junk.
Price Match Promise
Shipping around for the best price is tough, we make it easier by offering the best pricing in the market. But if you find a better price on an in-store item somewhere else we will match it!
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Product Description
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 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.
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 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 |
What can I see with a William Optics Ultra-Cat 131 WFID APO Petzval OTA | L-UC131?
Here are some simulated views of common objects. Results with your telescope will vary with viewing conditions, obrits, equipment and more.
Jupiter with
25mm Eyepiece - 26x Magnification
(Sold Separately)
Jupiter with
10mm Eyepiece - 65x Magnification
Sold Separately
Jupiter with
5mm Eyepiece - 130x Magnification
Sold Separately
Moon with 25mm Eyepiece
26x Magnification
(Sold Separately)
Moon with 10mm Eyepiece
65x Magnification
Sold Separately
Moon with 5mm Eyepiece
130x Magnification
Sold Separately
Andromeda with 36mm Eyepiece
18x Magnification
Sold Separately
Andromeda with 25mm Eyepiece
26x Magnification
(Sold Separately)
Andromeda with 10mm Eyepiece
65x Magnification
Sold Separately
