William Optics Mighty-Cat 71 – 30th Anniversary Limited Edition (William Optics, SKU: T-MC-71RD-30A) is an ultra-fast apochromatic astrograph developed specifically for wide-field deep-sky imaging. Its seven-element 71 mm EVO Petzval optical system, with a focal length of 230 mm and a focal ratio of f/3.2, provides a flat 43.2 mm image circle without requiring an additional field corrector. The anniversary version was produced as a limited run of 100 sets and features a red “Cosmic Visitor” finish with commemorative motifs celebrating 30 years of William Optics.

Key features

• ultra-fast f/3.2 optics reduce the exposure time required to record faint nebulae, dark dust clouds, and expansive celestial structures
• seven-element EVO Petzval design with three Super ED glass elements provides a naturally flat field without an additional flattener
• the manufacturer’s spot diagram for six field positions specifies an RMS spot radius from 0.686 µm to 1.977 µm, with an Airy disk radius of 2.234 µm
• 43.2 mm image circle supports full-frame cameras as well as APS-C and M4/3 sensors
• patented WIFD focuser moves an internal section of the optical system, helping maintain favourable balance and reduce flexure in the rear imaging train
• Sensor Tilt Xterminator STX-R enables precise sensor-tilt correction, while the integrated CAA rotator provides 360° camera rotation
• Anti-Shrink Lens Cell technology reduces the effect of temperature changes on the position and mechanical stress of the optical elements
• patented Bahtinov mask integrated into the front cover enables quick and accurate focusing
• patented carrying handle provides an additional mini Vixen-style mounting base
• limited red “Cosmic Visitor” finish and commemorative certificate emphasise the anniversary character of this edition

Set contents

• William Optics Mighty-Cat 71 30th Anniversary Limited Edition optical tube
• front lens cover with integrated Bahtinov mask
• M48 camera adapter
• M54 camera adapter
• camera adapter wrench
• dual-sided Vixen / Arca-Swiss mounting plate
• tube mounting ring with carrying handle
• Allen key set
• soft carrying case
• commemorative anniversary-edition certificate

Technical specifications

• type: apochromatic astrograph designed exclusively for astrophotography
• optical design: seven-element EVO Petzval system
• optical glass: three Super ED glass elements
• aperture: 71 mm
• focal length: 230 mm
• focal ratio: f/3.2
• image circle diameter: 43.2 mm
• supported sensor formats: full frame, APS-C, M4/3
• flattener required: no
• focuser: WIFD Rack & Pinion
• fine focusing ratio: 1:10
• focuser travel: 0–35 mm
• electronic focuser compatibility: EAF
• sensor-tilt adjustment: Sensor Tilt Xterminator STX-R
• camera rotator: integrated CAA with 360° scale
• camera connections included: M48 and M54
• recommended back spacing: 55 ± 3 mm
• mounting plate: dual-sided, Vixen / Arca-Swiss standard
• tube length: 315 mm
• optical tube weight: 3.38 kg
• total weight: 4.1 kg
• colour: red
• limited production run: 100 sets

The William Optics Mighty-Cat 71 combines an exceptionally fast f/3.2 optical system, a full-frame image circle, and advanced adjustment mechanics in a compact design intended for efficient imaging of expansive deep-sky objects.