
OVERVIEW
The William Optics UltraCat108 is a cutting-edge 108mm apochromatic refractor designed for astrophotographers who demand top-tier performance. Featuring a 5-element advanced Petzval optical design and a fast f/4.8 focal ratio, it delivers breathtaking edge-to-edge clarity and vivid detail, making it perfect for capturing expansive celestial views. Its robust build, exceptional optics, and innovative features redefine the standard for astrophotography.
WHAT'S IN THE BOX

MAIN TUBE

BAHTINOV CAP

M48, M54, M68 ADAPTER

VIXEN-STYLE MOUNTING PLATE

MOUNTING RING HANDLE BAR

SOFT CARRY CASE

ALLEN KEY SET

LET THE QUALITY SPEAKS
The UltraCat 108 embodies the pinnacle of optical engineering, merging a revolutionary 5-element Petzval design with cutting-edge features tailored for astrophotographers. Every detail—from its expansive image circle to its internal focuser and integrated tilt corrector—is crafted to deliver unmatched clarity, precision, and performance across the celestial canvas.


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.
NEVER EASIER TO CAPTURE DEEP SKY OBJECTS

COMPREHENSIVE CONFIGURATION
PRECISION IMAGING ADJUSTMENT

SENSOR TILT XTERMINATOR (STX)
The built-in STX allows quick side-access tilt adjustments without removing the camera.
Learn More
CAMERA ANGLE ROTATOR
Correct any angular discrepancies, and get the perfect angle on your images.

COMPATIBLE WITH ELECTRONIC MOTORIZED DEVICES
Hassle Free Installation
( No Mounting Bracket Kit required )
The new K-ASTEC mounting bracket (optional) is now avalible to make the EAF more streamline with the OTA.

LEADING THE MARKET
WO PATENTED DESIGN
The Ultra-Cat 108 holds three unique patents, ensuring easy and perfect focusing along with precise coaxial image quality, preventing draw tube tilt issues caused by optical misalignment.
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INTERNAL FOCUSER
The WIFD focusing Design relocates the focuser to the center of the telescope, addresses the issue of tube tilt caused by the weight of accessories and cameras.
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INTEGRATED BAHTINOV MASK
Laser engraved on high-definition and stable optical PMMA. Enhances astrophotography experience with quick and accurate adjustments.
CAT HANDLE BAR
Crafts for enhanced portability and versatility.
MOUNTING RING
Designed for seamless functionality without compromising on stability. Engineered with wide surface contacts, this innovative ring ensures a secure fit while enabling fast, easy detachment.

SPECIFICATION
- 5-Element Advanced Petzval
- Lens Elements
- Super ED Glass x2
- ED Glass x1
- Lanthanum Glass x1
- X-Element x1
- Focal Length
- 518 mm
- Diameter
- 108 mm
- Focal Ratio
- f/4.8
- Image circle
- 60 mm
- Focuser
- WIFD R&P Focuser
- Compatible with EAF
- Adapter Included
- Sensor Tilt Corrector
- Rotator
- M68, M54, M48 Camera Adapters
- Optional Flattener
- No Flattener Required
- T-Mount Supported
- 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
- Tube Length
- 510.5 mm - 588.5 mm
- OTA Weight
- 7.95 kg / 17.53 lbs
- Total Weight
- N/A

Buy risk-free: When it’s time to trade up you’ll get the most value for your used gear.