WILLIAM OPTICS ULTRA-CAT 108 f/4.8 REFRACTOR

 

 

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.

 

 

Innovative 5-Element Petzval Design

Eliminates field curvature, providing sharp, flat-field images without requiring additional flatteners. This advanced system achieves a flawless spot diagram across a medium-format image circle.

This new system does NOT have specific requirement for the backfocus, however the focus travel distance can effect the ability to find the focus if there is too much space between the telescope and the acquisition device. 

 

 

60mm Superior Image Circle

Fully supports full-frame and medium-format cameras for wide-field and detailed astrophotography, outperforming standard 106mm telescopes. 

Extra-Low dispersion ED Glasses

The Ultra-Cat 108 has 2 Super ED, 1 ED glasses and lanthanum lenses with advanced fully multi-coated, to deliver sharp and vibrant images with true colors, reducing chromatic aberration.

 

F/4.8 Fast Optics

Offers exceptional light-gathering capability for vibrant deep-sky photography.

 

WIFD (William’s Internal Focuser Design)

Patented internal center balanced focuser ensures precise, stable, and hassle-free imaging, avoiding balance issues and eliminating vignetting. The WIFD system solves the issue of tube tilt caused by the excessive weight of accessories and cameras.

With its its precise internal sliding and balanced rigid, structure the Ultra-Cat 108 prevents image shift and weight limits for photographic equipment. 

The Rack & Pinion designed for the WIFD provide accurate and smooth focusing for both imaging and visual observation. Fine-tuning can be achieved thanks to 1:10 fine focuser.

Temperature can be immediately checked with the gauge installed in one of the knobs.

 

 

Anti-Shrink Lens Cell Technology

Minimizes thermal expansion and contraction, maintaining perfect optical alignment in any environment.

 

 

Sensor Tilt Corrector

The Sensor Tilt Xterminator (STX) allows to adjust the tilt without removing the camera. With its integrated and patented design eliminates distortion, optimizing sharpness and detail for professional-level results. This new system is an evolution of the old 4 pull-in and 8 push-out screws, with a more efficient 4 pull-in and 4 tension screws mechanism makes easier and effortless any correction.

 

 

Camera Rotator

As all the William Optics refractors, the Ultra-Cat 108 come with a camera rotator build in multiple material to avoid any pinching due to temperature changes. Smooth and precise control of the adjustments are provided by an oil-sealed mechanism and the laser-engraved angle scale of the components.

 

 

Off-axis guide

If you want to instal an off-axis guide you will need to remove the rotator screw with the knob and replace it with the include H4 set screw.

 

 

Built-In Patented Bahtinov Mask

The dust cap has an integrated Bahtinov Mask to simplify focusing for pinpoint precision, a feature that reduces the equipment needed saving space. The mask is made in a high-transparent optical acrylic (PMMA) cut with precision laser, for a better transmission of the light and more accurate focus..  

 

 

Mounting Solutions

The Ultra-Cat 108 is equipped with an universal M6 and M4 threaded holes allowing easy installation of guide/finder scopes, computers and other accessories. it combines ergonomic usability with enhanced portability. 

 

Diagram Report

SPECIFICATIONS

Lens type:	5-Element Advanced Petzval
Lens elements:	Super ED, ED, Lanthanum, X-Element
Focal length:	518mm
Diameter:	108mm
Focal ratio:	f/4.8
Image circle:	60mm
Focuser:	WIFD R&P Focuser, compatible with EAF
Focus travel:	0-30mm
Adapter included:	Sensor Tilt Xterminator, Rotator and 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 and M4/3
Tube length:	512.9mm to 617.9mm
OTA weight:	7.82kg

 

For an optimal light control and image quality, the camera sensor will need top be set at 52-58 mm from the telescope connection.

 

 

Items included

 

• Ultra-Cat 108
  
• Lens cover with Bahtinov mask and cover
• M79 to M48, M54 and M68 adapter with dust cap
• Handle bar with mini Vixen mounting base
• Mounting ring with Vixen dovetail
• 50mm Guide scope
• William Optics bag for Ultra-Cat 108
• Allen key set

 

Instruction Tilt Adjuster (STX)

Installing EAF