William Optics UltraCat 56 WIFD — 56 mm Petzval astrograph The 5-element optical system provides a 269 mm focal length at f/4.8, with a 50 mm image circle. Its Petzval design does not require an external field flattener.
Manufacturer model: William Optics UltraCat 56 WIFD · Specifications checked against manufacturer data on 2026-11-03
The 5-element optical system provides a 269 mm focal length at f/4.8, with a 50 mm image circle. Its Petzval design does not require an external field flattener.
The WIFD rack-and-pinion focuser provides 30 mm travel and 1:10 fine adjustment. A camera rotator controls framing, while the Sensor Tilt Xterminator allows sensor alignment. The lens cover incorporates a Bahtinov focusing mask.
STX tilt adjuster / rotator; interchangeable M68 to M48 and M68 to M54 adapters. Petzval focus depends on the complete camera train remaining within the telescope's focusing range.
The tube length is 296.3–348.3 mm. OTA weight is 2.56 kg and the manufacturer specification table lists 3.21 kg total weight. The mounting plate is 210 mm Vixen-style / Arca-Swiss dual-sided.
William Optics manufacturer manual
William Optics specifies two Super ED elements, one ED element, one lanthanum element and one X-element in the five-element optical system. The internal focuser moves the focusing mechanism within the telescope, while the rear tilt and rotation adjustments support sensor alignment and framing.
Petzval focus range must accommodate the complete imaging train; do not interpret recommended camera spacing as an exact flattener backfocus. Confirm supplied adapters and revision.
Data sheet
William Optics UltraCat 56 WIFD — 56 mm Petzval astrograph The 5-element optical system provides a 269 mm focal length at f/4.8, with a 50 mm image circle. Its Petzval design does not require an external field flattener.
Manufacturer model: William Optics UltraCat 56 WIFD · Specifications checked against manufacturer data on 2026-11-03
