William Optics RedCat 91 WIFD APO f/4.9 (red version)

William Optics RedCat 91 WIFD APO f/4.9

Advanced Optical Design for Unmatched Performance

A High-End Apochromatic Refractor for Demanding Astrophotographers

The RedCat 91 WIFD from William Optics is a premium apochromatic refractor designed to meet the expectations of the most meticulous astrophotographers. With a 91 mm aperture and a 448 mm focal length (f/4.9), it provides an ideal focal ratio for wide-field and deep-sky imaging.

Its 5-element Petzval optical design eliminates the need for an additional field flattener, ensuring optimal field flatness and outstanding correction of chromatic and spherical aberrations.

Optical Assembly

The optical system consists of:

• Two Super ED glass lenses for advanced chromatic correction
• One ED lens ensuring optimal light transmission
• One lanthanum element for exceptional color fidelity
• A fifth field correction element ensuring uniform sharpness across the entire sensor surface

With a 55 mm corrected image circle, the RedCat 91 WIFD fully utilizes full-frame sensors, providing high-resolution imaging from the center to the edges of the field.

Precision Focusing System with WIFD Technology

The RedCat 91 WIFD features the William Internal Focus Design (WIFD), an exclusive internal focusing system that optimizes the weight distribution of accessories while eliminating any risk of sensor tilt or shift.

• Patented central focusing system ensuring smooth and precise internal lens movement
• 36 mm focusing range with a 1:10 fine reduction ratio for ultra-precise adjustments
• No optical shift, ensuring increased stability in long-exposure imaging

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Precision Engineering & Universal Compatibility

The mechanical design of the RedCat 91 WIFD is based on a high-precision machined aluminum tube, offering an excellent rigidity-to-weight ratio.

• Optical tube length: 556 mm
• Weight (without accessories): 4.72 kg | Total weight: 6.3 kg
• Material: High-strength anodized aluminum

The instrument comes with a complete set of adapters and accessories, ensuring extensive compatibility with various astrophotography setups:

• M48 and M54 adapter rings
• Integrated tilt adjuster for optimal sensor alignment
• 360° field rotator

Technical Specifications

Box Contents

• RedCat 91 WIFD Refractor
• Laser-etched Bahtinov Mask
• M48 and M54 Adapters
• 290 mm Vixen / ArcaSwiss Dovetail Plate
• CAT Mounting Rings and Carry Handle
• Soft Carrying Case
• Allen Key Set

Why Choose the RedCat 91 WIFD?

• Advanced optical correction with a 5-element Petzval design
• 55 mm corrected image circle, ideal for full-frame sensors
• WIFD internal focusing system ensuring maximum precision
• Robust yet lightweight mechanical design, made from aerospace-grade materials
• Comprehensive accessory set, allowing seamless integration into your setup

The William Optics RedCat 91 WIFD is a high-end solution for astrophotographers seeking a compact, high-performance instrument optimized for large sensors. Its meticulous design and technical specifications make it an essential choice for capturing exceptionally precise astrophotographic images.

Notice:

Astrophotography Only
This telescope is specifically designed for astrophotography, and its optical design does not support visual observation.

Tension screw
When using the telescope with the motor, please ensure that the tension screw is not over-tightened. Over-tightening the tension screw may cause damage to the focuser.
Think of it like driving a car and pressing the gas pedal while also pressing the brake simultaneously. Just as this action could harm your car's systems, over-tightening the tension screw could compromise the functionality of your telescope's focuser.