William Optics RedCat 91 WIFD 30th Anniversary Edition A 91 mm Petzval astrograph with 448 mm focal length at f/4.9. The 55 mm image circle accompanies a five-element design using Super ED, ED and lanthanum glass.
Manufacturer model: William Optics RedCat 91 WIFD 30th Anniversary Edition · Specifications checked against manufacturer data on 2026-11-03
A 91 mm Petzval astrograph with 448 mm focal length at f/4.9. The 55 mm image circle accompanies a five-element design using Super ED, ED and lanthanum glass.
No separate field flattener is needed. WIFD rack-and-pinion focusing provides 36 mm travel. A sensor tilt adjuster and camera rotator support alignment and framing.
M63 to M54; M63 to M48 adapters connect the camera train. Maximum listed backspacing is 60.8 mm through M48 or 65.8 mm through M54. The mounting plate uses Vixen-style profiles.
Tube length: 556 mm. OTA weight: 4.72 kg; total weight: 6.3 kg.
William Optics manufacturer specifications
This model is designed for astrophotography; William Optics states that its optical design does not support visual observing.
Anniversary edition source used. Maximum spacing depends on rear adapter; confirm reference surface and supplied edition.
| Maximum m48 backspacing (mm) | 60.8 |
|---|---|
| Maximum m54 backspacing (mm) | 65.8 |
| Focusing aid | Bahtinov mask integrated into front cover |
Ficha técnica
William Optics RedCat 91 WIFD 30th Anniversary Edition A 91 mm Petzval astrograph with 448 mm focal length at f/4.9. The 55 mm image circle accompanies a five-element design using Super ED, ED and lanthanum glass.
Manufacturer model: William Optics RedCat 91 WIFD 30th Anniversary Edition · Specifications checked against manufacturer data on 2026-11-03
