William Optics WIFD RedCat 91 APO Refractor

Please Note: The free 32 mm UniGuide will be included within the telescope box.

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Stellar Scope with Massive Medium Format Coverage!

Bring the premium Petzval performance of William Optics' incredible RedCat line to your large sensor setup with this scope! Supporting cameras as large as medium-format, this refractor can illuminate just about any imaging equipment you can throw at it with powerful, punchy, and clear images of the awe-inspiring objects above. If you're looking for a wide-field, ready for any equipment, no fuss backfocus, and high-quality astrophotography platform then the William Optics WIFD RedCat 91 APO Refractor is for you!

William Optics' RedCat line has made a name for itself with its excellent performance, wide field of view, and sharp appearance. The William Optics WIFD RedCat 91 APO Refractor continues this lineage, bringing this renowned experience to massive medium-format imagers and those in search of more aperture alike! With a Petzval design, the RedCat 91 provides its stunning, sharp, dynamic, and clear views across a 55 mm image circle; no extra field flattener required! As long as you can reach focus with your gear you can capture incredible images of both the Heart and Soul Nebulae with a medium-format camera, vibrant images of Andromeda through a full-frame, or crisp shots of the Rosette Nebula from your APS-C camera. This incredible 448 mm focal length view of the universe is rendered in powerful clarity, contrast, detail, and color thanks to the Super ED, ED, and lanthanum lens combo in its five element design. With a f/4.9 focal ratio this 91 mm scope is quick, quickly collecting excellent images and putting you on the fast track to incredible results! This optical performance is supported by William Optics' WIFD focuser system alongside other great-to-haves like a camera rotator, M48 and M54 adapters, a built-in tilt adjuster, and a combo dust cover/ Bahtinov mask. With all these features and outstanding performance, the William Optics WIFD RedCat 91 APO Refractor cements itself as another standout refractor from William Optics!

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Seagull Nebula, ZWO ASI2600MC Air, Optolong L-Para and Askar D2 Color Magic Filters, 7.5 Hours Total Integration Time

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What Does Our Team Think?

• "This was my first experience with a William Optics RedCat telescope, so I was thrilled to try the 91 mm, especially since it was one of their newer models. The quality and performance did not disappoint. It felt solid and high-end, with a noticeable heft from the glass inside. This was also my first experience with William Optics' internal focusing design and installing the EAF was quick and easy as well. Focusing was silky smooth, delivering perfectly sharp stars. The dovetail had the look and stability of a Losmandy-style but was actually a sturdy Vixen. I was impressed by the 91 mm aperture and fast f/4.9 speed, which helped me capture stunning, colorful details of the Seagull Nebula much faster than typical f/6 or f/7 refractors at a similar aperture. One of my favorite features was the camera angle rotation device, which made framing my target incredibly smooth and precise. Every aspect of this telescope exudes quality, and the data it captured was simply exquisite!"

- Diana P., High Point Scientific Gear Expert

Tame Tilt

The William Optics WIFD RedCat 91 APO Refractor comes equipped with a built-in tilter to help compensate for tilt in your imaging train. Accessing this handy accessory is a straight forward process, requiring only the included tools to adjust the tilter itself. Begin by unthreading and completely removing the camera angle adjuster's tension knob. Then unthread the camera angle adjuster's angle guide ring, which will expose the tilt adjustment ring. From here you can adjust tilt with the included hex key set! The three adjustment points feature a set of Push-Pull-Push screws; adjust these as desired, then reinstall the angle guide ring and tension knob to complete the tilt adjustment process!

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Integrate Your Imaging Filter

For single-filter session shooters the RedCat 91 features a 2" filter cell in its M48 adapter to allow you to seamlessly integrate an imaging filter into your setup! To install your astrophotography filter of choice, simply lock the camera angle knob down, unscrew the M63 to M48 adapter, and thread the filter into the female 2" filter threads on the M63 side*. Reinstall the M63 to M48 adapter, and you're ready to image!

*To make uninstalling your delicate filter just as easy, William Optics advises that a small amount of lubricating oil is added to the threads of the filter prior to threading it into the filter cell.

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Large RedCat Optical Powerhouse

91 mm crystal clear Petzval optics, RedCat performance, William Optics' excellent WIFD system, and a solid suite of included accessories combine to make the William Optics WIFD RedCat 91 APO Refractor a standout large astrophotography refractor!

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Large Refractor Optics, Expansive Sensor Coverage, Big Performance
With a 91 mm objective lens at the front of the William Optics WIFD RedCat 91 APO Refractor's f/4.9 Petzval optical arrangement, this scope provides a bright, wide, and crystal clear look at the universe's wonders. With two Super ED, one ED, and Lanthanum lenses making up its five element system you can reveal the ethereal wisps of a nebula or the spectacular spirals of a galaxy in sharp detail, intense contrast, and excellent color correction. This arrangement provides this incredible performance across an impressive 55 mm image circle without an additional field flattener needed, allowing you to cover even massive medium-format sensors with minimal backfocus fuss.

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Rigid WIFD Focusing System
The William Optics Internal Focusing Design (WIFD) takes traditional refractor focuser designs and turns them on their head, giving you an equipment mount that is incredibly robust! While more common designs attach your imaging gear to a tube that moves towards/away from the optics, William Optics' patented WIFD system moves the optics while keeping your gear locked in place. This swap means that your gear can be attached to the rigid telescope "frame" which is not prone to the same droop/tilt concerns of a traditional drawtube (especially at full extension!). With the rack and pinion needing to only support the weight of the optics, it can be calibrated for smooth, backlash-free, tilt-free, and accurate focusing. This focuser is additionally EAF-ready out of the box, allowing you to easily add some of the excellent electronic focusers on the market today like the ZWO Standard Electronic Automatic Focuser . With the WIFD at your scope's core, you'll have solid support for even demanding medium-format imaging trains!

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What's In The Box?
The William Optics WIFD RedCat 91 APO Refractor comes with a stellar suite of included accessories to get you up and running on day one! Carrying the scope is a set of sleek red anodized rings, equipped with large clamp knobs and a combo Synta accessory top rail/ handle bar that can easily carry your guide scope or WiFi Camera Controller. Connecting these to your mount is a hybrid dovetail bar; featuring an expansive D-style top plate and V-style dovetail connection that gives you excellent equipment real estate with wide mount compatibility. Riser blocks are included to help give additional clearance under the scope when using accessories like ZWO's EAF. Protecting the front of the scope when it is not in use is a red anodized dust cap with a removable lid; which when removed exposes a built-in Bahtinov mask! This helps ensure you can focus your gear wherever you are; and attaching this gear has been made simple with the included M48 and M54 adapters, which cover the wide variety of cameras spanning all the way to full-frame and dual sensor (medium-format will require an adapter). An included hex key set helps in setting up your RedCat 91 and adjusting the tilt, and the foam padded soft case keeps everything safe and secure when you're breaking down and transporting the scope!