William Optics Cat 91 WIFD
Step up your astrophotography game with the William Optics RedCat 91, an advanced apochromatic refractor tailored for full-frame and medium-format cameras. This latest addition to the RedCat series combines portability with superior optical performance, making it a versatile tool for capturing breathtaking detail in deep-sky objects.
Highlights:
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Petzval Design, No Backfocus Hassles: The 5-element Petzval design eliminates the need for backfocus adjustments, providing sharp, edge-to-edge images with pinpoint stars—ideal for wide-field and detailed astrophotography alike.
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Full-Frame & Medium-Format Ready, No Extra Flattener Needed: With a large 50mm image circle, the RedCat 91 is perfect for both full-frame and medium-format cameras. Its advanced optics achieve flat-field images without requiring an additional flattener, giving astrophotographers the freedom to capture expansive views with unparalleled clarity.
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Fast f/4.9 Focal Ratio: The RedCat 91's fast f/4.9 focal ratio is designed for bright, vivid captures of galaxies, nebulae, and beyond, ensuring excellent light-gathering power and sharp detail even on faint celestial objects.
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Seamless WIFD Focusing: Equipped with William Optics' WIFD focuser, the RedCat 91 provides precise, stable focusing without additional adjustments, enhancing the ease of use for both seasoned astrophotographers and beginners.
The RedCat 91 blends the trusted RedCat heritage with William Optics’ innovative design, making it the ultimate choice for those ready to elevate their night-sky explorations.
The cat with medium-format soul
An advanced apochromatic refractor tailored for full-frame and medium-format cameras. This latest addition to the RedCat series combines portability with superior optical performance, making it a versatile tool for capturing breathtaking detail in deep-sky objects.
Advanced Petzval
Researched and developed by WO, the innovative 5-element Petzval design redefines telescope optics. This advanced system achieves a flawless spot diagram across a medium-format image circle.
Extra-low Dispersion (ED) glasses
Contains 2 Super ED, 1 ED glasses and lanthanum lenses with advanced fully multi-coated, delivering sharp, vibrant images with true-to-life colors, significantly reducing chromatic aberration.
Needs NO Flattener
The Petzval design inherently flattens the field, eliminating the need for an external field flattener.
Compatible with Electronic Motorized Devices
Hassle Free Installation
( No Mounting Bracket Kit required )
Internal Focuser
The WIFD focusing Design relocates the focuser to the center of the telescope, addresses the issue of tube tilt caused by the weight of accessories and cameras
Technical Specifications
Lens Type : 5-Element Advanced Petzval
Lens Elements : Super ED Glass x2 ED Glass x1 Lanthanum Glass x1
Focal Length : 448 mm
Diameter : 91 mm
Focal Ratio : f/4.9
Image circle : 55 mm
Focuser : WIFD R&P Focuser Compatible with EAF
Focus : travel 0-36mm (Ruler to 40mm)
Adapter Included : Tilt Adjuster Rotator M63 → M54 Adapter M63 → M48 Adapter
Optional Flattener : No Flattener Required
T-Mount Supported : Canon EF, RF Nikon F, Z Sony E Pentax K MFT (M4/3) FUJI X
Camera Format : Medium Format ( needs additional adapter ) Full Frame APS-C M4/3
Tube Length : 556 mm
OTA Weight : 4.72 kg / 10.41 lbs
Total Weight : 6.3 kg / 13.89 lbs
In the Box
-William Optics Cat 91 WIFD
-Bahtinov Cap
-M48 & M54 Adapter
-Mounting Plate
-Mounting Ring Handle Bar
-Soft Carry Case
-Allen Key Set
Warranty & Manual
William Optics 2-year Warranty
