William Optics RedCat 71 WIFD APO f/4.9

William Optics RedCat 71/350 Apochromatic Refractor – A High-Performance Astrograph for Astrophotography and Sky Observation

This latest version of the Redcat 71 features the same tried-and-tested optics as previous versions, so it provides high-resolution images when used for astrophotography or wildlife photography. 

Its fast f/4.9 focal ratio and compact size make it ideal for convenient wide-field astrophotography, and the WIFD (William Optics Internal Focuser Design) is integrated inside the main tube assembly, so no focuser drawtube movement is visible from the outside. 

One of the most significant benefits of the WIFD is that you can add several heavy accessories to your imaging train, such as a large filter wheel or rotator, without worrying about sag from the telescope focuser drawtube and the resultant tilt of the sensor with reference to the optical axis.

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Designed primarily for astrophotography, the RedCat 71 provides a flat image plane (without needing an additional flattener), an image circle over 45mm, excellent colour correction and pinpoint stars. 

Key Features of the RedCat 71:

• Astrograph with integrated corrector: Designed for astrophotography up to full-frame, the RedCat 71 ensures optimal correction and an illuminated image field without chromatic aberration, thanks to its Petzval design with four elements, including FPL-53 and FPL-51 glass.
• Aperture of 71 mm / Focal Length of 350 mm / Focal Ratio f/4.9: Perfect for capturing fine details in deep-sky objects.
• Ultra-precise helical focusing system: Easy and fast focusing, similar to traditional manual focus photo lenses.
• 360° Rotation for total flexibility: Adjust your camera orientation for perfect framing with the graduated rotation ring.
• Quick and easy connection: M48x0.75 mm male thread for simple mounting with an optimal back focus distance of 55 mm.
• Included anti-tilt ring: Adjust the tilt of the sensor for perfect focus without distortion.

Additional Features:

• Durable aluminum construction: Lightweight (2.8 kg for the tube alone) and built to last, designed for outdoor use.
• Anti-reflective multi-coating FMC: On all optical surfaces for sharp, high-contrast images.
• Compatible with standard photo tripods: With a Vixen-style dovetail plate, Arca-Swiss compatibility, and a Kodak 1/4" thread, this refractor fits most mounts and tripods.
• Included Accessories: A nylon carrying case for protection, a Bahtinov mask for easy astrophotography focusing, and an M48 adapter for rear filter attachment.
• Precise Focusing: With the patented WIFD focusing system, you get ultra-precise focusing, protected from the elements, with instant numerical focus position monitoring.

Ideal for:

• Astrophotography: Capture high-quality images of celestial objects with a dedicated astrograph, offering a corrected field of view up to full-frame.
• Daytime Photography: Perfect for nature and wildlife photography during the day, thanks to its intuitive and precise focusing system.

Technical Specifications:

• Type: Astrograph with integrated corrector
• Construction Type: Apochromatic, Petzval quadruplet (4 lenses) APO
• Aperture: 71 mm
• Focal Length: 350 mm
• Focal Ratio: f/4.9
• Theoretical Resolution: 1.94 arcsec
• Limiting Magnitude: 12.3
• Focusing System: WIFD
• Light-gathering Capacity: 100x the human eye
• Maximum Useful Magnification: 142x
• Material: Aluminum
• Optical Coating: FMC multi-coating on all optical surfaces
• Dew Shield Diameter: 103 mm / Dew Shield Length: 435 mm
• Tube Weight: 2.8 kg (tube alone) / 3.7 kg (with accessories)

Included Accessories:

• Astrograph with dew shield and integrated field corrector
• Nylon transport case
• M48 adapter ring with tilt correction and 360° rotation
• Bahtinov mask (integrated in the lens cap)
• Vixen-style dovetail plate (210 mm) and ArcaSwiss compatibility