RedCat 71 Optical Design

The William Optics RedCat 71 is the bigger brother to the highly-regarded RedCat 51, which has been raved about by astrophotographers since its release. Building on the RedCat 51's success, the RedCat 71 keeps the same f/4.9 focal ratio and Petzval optical design. This optical design uses four lens elements instead of the three found in triplet refractors. By incorporating this extra element, the RedCat 71 is able to achieve a flat field without the need for an additional field flattener.

RedCat 71 Image Circle & Camera Compatibility

The flat field image circle on the WO RedCat 71 is over 45mm in diameter, meaning it can provide round stars to the corners on a full frame camera, not something many telescopes can claim in this price range. The RedCat 71 telescope comes with a 48mm thread on the back, meaning you can easily attach any dedicated astronomy camera with a standard M48x0.75 connection such as ZWO. For DSLR and mirrorless users, simply add an M48 t-ring for your camera type and you'll be ready to do astrophotography right out of the box.

Designed for Wide Field Astrophotography

The RedCat 71's focal length of 350mm is ideal for wide field astrophotography of large nebulae, galaxies, and the Milky Way. The shorter focal length also makes it very forgiving for beginners because it doesn't require as precise of tracking with a mount. Please note that the new WIFD RedCat series telescopes cannot be used visually at this time, but this could change in the future with the addition of accessories.

Game-Changing WIFD Focuser

New in the third generation of the RedCat 71, this telescope features William Optics' new patented WIFD focuser. This game-changing design allows the telescope to focus by moving lens elements internally instead of externally. This has numerous benefits, including reducing vignetting, focuser sag, and most importantly, sensor tilt. The WIFD focuser is also compatible with the ZWO EAF out of the box, unlike previous versions of the RedCat 71.

RedCat 71 Specifications

• Optical Design: Petzval (4-element)
• Glass Type: FPL-53
• Focal Length: 350mm
• Aperture: 71mm
• Focal Ratio: f/4.9
• Image Circle: 45mm (full frame)
• Focuser: William Optics Internal Focus Design (WIFD)
• Focuser Compatibility: ZWO EAF
• Tube Length: 427mm
• Dew Shield Circumference: 331mm
• Dew Shield Diameter: 105mm
• Weight of OTA only: 7.1 lbs (3.2 kg)
• Weight of OTA with tube rings, dovetail, & saddle: 9.5 lbs (4.3 kg)
• Soft Carrying Case External Dimensions: 49x23.5x27 (cm)