William Optics RedCat 61 OTA — 61 mm Petzval astrograph The 4-element optical system provides a 300 mm focal length at f/4.9, with a 46 mm image circle. Its Petzval design does not require an external field flattener.
Manufacturer model: William Optics RedCat 61 OTA · Specifications checked against manufacturer data on 2026-11-03
The 4-element optical system provides a 300 mm focal length at f/4.9, with a 46 mm image circle. Its Petzval design does not require an external field flattener.
The WIFD rack-and-pinion focuser provides 42 mm travel and 1:10 fine adjustment. A camera rotator controls framing, while a sensor tilt adjuster allows sensor alignment. The lens cover incorporates a Bahtinov focusing mask.
Tilt adjuster; M60 to M54 rotator; M54 to M48 adapter. The M48 adapter incorporates an internal filter thread. Petzval focus depends on the complete camera train remaining within the telescope's focusing range.
The tube length is 365 mm. OTA weight is 2.47 kg and the manufacturer lists 3.39 kg total weight. The mounting plate is 210 mm Vixen-style / Arca-Swiss dual-sided.
William Optics manufacturer manual
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.
Ficha técnica
William Optics RedCat 61 OTA — 61 mm Petzval astrograph The 4-element optical system provides a 300 mm focal length at f/4.9, with a 46 mm image circle. Its Petzval design does not require an external field flattener.
Manufacturer model: William Optics RedCat 61 OTA · Specifications checked against manufacturer data on 2026-11-03
