WILLIAM OPTICS ULTRA-CAT 56 f/4.8 REFRACTOR

The William Optics UltraCat56 is a high performance 56mm 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 details, 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. 

50mm Superior Image Circle

Fully supports full-frame and medium-format cameras for wide-field and detailed astrophotography, outperforming standard ~60mm telescopes. 

Extra-Low dispersion ED Glasses

The Ultra-Cat 56 has Super ED glasses and lanthanum lenses with advanced fully multi-coated, to deliver sharp and vibrant images with true colours, 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 centre 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-Cat56 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 56 come with a camera rotator build in multiple material to avoid any pinching due to temperature changes. The camera rotator is integrated with the Sensor Tilt Xterminator. Smooth and precise control of the adjustments are provided by an oil-sealed mechanism and the laser-engraved angle scale of the components.

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 56 is equipped with an universal M6 and M4 threaded holes allowing an easy installation of guide/finder scopes, computers and other accessories. It combines ergonomic usability with enhanced portability. 

Diagram Report

SPECIFICATIONS

Items included

• Ultra-Cat 56
• Lens cover with Bahtinov mask and cover
• M68 to M48, M54 adapter with dust cap
• Handle bar with mini Vixen mounting base
• Mounting ring with Vixen dovetail
  
• William Optics bag for Ultra-Cat 56
• Allen key set

Instruction Tilt Adjuster (STX)

Installing EAF