Skip to content

Country

William Optics Cat 91 WIFD (Pre-order, ships in one week)

SKU WO-T-C-91
Original price $2,598.00 USD - Original price $2,598.00 USD
Original price
$2,598.00 USD
$2,598.00 USD - $2,598.00 USD
Current price $2,598.00 USD

Description

  • Petzval Design, No Backfocus Hassles
  • Full-Frame & Medium-Format Ready, No Extra Flattener Needed
  • Fast f/4.9 Focal Ratio
  • Seamless WIFD Focusing
Availability:
Backordered
Contact us to know when we will receive our next ones!
Availability:
Backordered
Contact us to know when we will receive our next ones!

Free Shipping in USA

More information

  • Description
  • Specifications
  • In the Box
  • Downloads
  • 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.
    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.

    William Optics Petzval

    Extra-low Dispersion (ED) glasses


    Extra-low Dispersion (ED) glasses

    Needs no flattener


    The Petzval design inherently flattens the field, eliminating the need for an external field flattener.

    https://williamoptics.com/cdn/shop/files/series-Diagram_Cat-91_1.jpg?v=1728272268&width=800

    Never easier to capture deep sky objects


    https://williamoptics.com/cdn/shop/files/FOV-cat91-C-02.jpg?v=1730707560&width=1600

    Compatible with Electronic Motorized Devices


    Hassle Free Installation ( No Mounting Bracket Kit required )

    https://williamoptics.com/cdn/shop/files/Cat-91-WIFD-EAF.jpg?v=1730708811&width=1000

    Wo patented design


    The Cat 91 holds three unique patents, ensuring easy and perfect focusing along with precise coaxial image quality, preventing draw tube tilt issues caused by optical misalignment.

    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.

    https://williamoptics.com/cdn/shop/files/WIFD-grey_line.gif?v=1727934296&width=800

    CAT Handle Bar


    Crafts for enhanced portability and versatility.
    Designed for seamless functionality without compromising on stability. Engineered with wide surface contacts, this innovative ring ensures a secure fit while enabling fast, easy detachment.

    https://williamoptics.com/cdn/shop/files/Cat-91-WIFD-whatsinbox-mounting.png?v=1728630077&width=800

    Integrated Bahtinov mask


    Laser engraved on high-definition and stable optical PMMA. Enhances astrophotography experience with quick and accurate adjustments.

  • Lens Type

    5-Element Advanced Petzval

    Lens Elements

    Super ED Glass x2

    ED Glass x1

    Lanthanum Glass x1

    X-Element 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

    Yes

    Focus Travel

    0-36 mm (Ruler to 40 mm)

    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

    • Main Tube
    • Bahtinov Cap
    • M48 & M54 Adapter
    • Mounting Plate
    • Mounting Ring Handle Bar
    • Soft Carry Case
    • Allen Key Set

Customer Reviews

Be the first to write a review
0%
(0)
0%
(0)
0%
(0)
0%
(0)
0%
(0)