AP 76/365 UltraCat 76 WIFD apochromatic AP 76/365 refractor

UltraCat 76/365 WIFD AP 76/365 Apochromatic Refractor

Ultra-Cat 76 - 76mm Apochromatic Refractor for Advanced Astrophotography

The Ultra-Cat 76 is a powerful 76mm apochromatic refractor designed for demanding astrophotographers seeking the highest optical quality in every image. With a 5-element Petzval optical design, including Super ED glass and lanthanum, and a fast f/4.8 aperture ratio, this telescope delivers stunningly sharp images with a flat 50 mm field, without the need for an external field flattener. Its optical design naturally corrects field curvature, ensuring chromatically pure and perfectly flat images.

Optimized for all sensor types

The Ultra-Cat 76 is designed to work excellently with full-frame, APS-C and M4/3 sensors, and is also compatible with medium format cameras, making it an ideal tool for high-quality wide-field astrophotography.

Accurate and stable focusing

The telescope incorporates William Optics' innovative WIFD internal focusing design, which combines a patented internal focusing mechanism with the highest quality optics available. This allows precise focuser movement without affecting optical stability, even with large, heavy, cooled cameras. The focuser position remains constant throughout the night thanks to the lens cell designed to minimize thermal expansion.

The focuser includes two fine focus positions and is compatible with ZWO EAF, providing full control over sharpness without the usual vignetting problems of conventional rear-mounted focusers. In addition, it has an integrated numerical indicator window that allows the exact focus position to be checked at any time.

Accessories and additional features

• Integrated Bahtinov mask: facilitates accurate focusing of the sensor.

• Tilt Xterminator (STX) sensor and integrated rotator: prevents loss of sharpness caused by tilt and allows the sensor to be optimally oriented towards the object.

• Spray hood and carrying bag included.

• Vixen -styleplate for secure mounting.

• Integrated corrector for a completely flat field.

• UniGuide 32 mm spotting scope included.

Recommended applications

• Deep and wide field astrophotography: outstanding

• Moon and planets: yes

• Nebulae and galaxies: yes

• Sun: only with suitable solar filter

• Nature observation: no

• Recommended for: advanced users and professional setups

Technical specifications

• Aperture: 76 mm

• Focal length: 365 mm

• Focal ratio: f/4.8

• Resolution capability: 1.82

• Magnification limit: 11.2

• Light gathering capacity: 120x

• Maximum useful magnification: 152x

• Tube weight: 4.98 kg

• Tube length: 415 mm

• Transport length: 363 mm

• Tube material: aluminum

• Optical design: Petzval triplet

• Fully corrected field: 50 mm

• Internal focusing: WIFD, with integrated tilt and rotator

Conclusion

The Ultra-Cat 76 is a telescope designed from the ground up for advanced astrophotography, combining the best Petzval optics with an innovative internal focuser and professional accessories that guarantee sharp, flat and chromatically pure images. Its compatibility with large and medium sensors, together with mechanical stability and precision, make it an ideal choice for demanding astrophotographers looking for professional quality from the first use.

AP 76/365 UltraCat 76 WIFD apochromatic AP 76/365 Refractor