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
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.
Focus and camera alignment
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.
Imaging connections
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.
Size and mounting
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.
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.
79115
Datasheet
Opening (mm)
61
Camera-adapters
Tilt adjuster; M60 to M54 rotator; M54 to M48 adapter
Cameraformaat
Full frame, APS-C and Micro Four Thirds
Camerarotatie
Camera angle rotator
Elektronische focus
ZWO EAF compatible; use the manufacturer installation guide for the selected EAF model.
Externe veldvlakker vereist
No
Overbrenging fijnfocus
1:10
Brandpuntsafstand (mm)
300
Openingsverhouding
4.9
Focuser
WIFD rack-and-pinion
Focuserslag (mm)
42
Focusmasker
Bahtinov mask incorporated in lens cover
Beeldcirkel (mm)
46
Inwendige M48-filterschroefdraad
Yes
Montageplaat
210 mm Vixen-style / Arca-Swiss dual-sided
Optisch ontwerp
4-element Petzval
Gewicht optische tubus (kg)
2.47
Tiltafstelling sensor
Sensor tilt adjuster
Totaalgewicht (kg)
3.39
Tubuslengte (mm)
365
Dit product gebruikt? Deel je ervaring met andere astronomen.
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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
