The William Optics WIFD RedCat 91 APO is an advanced apochromatic refractor designed specifically for astrophotography. This telescope is part of the popular William Optics RedCat series, known for its exceptional optical performance and innovative design.
The RedCat 91 features a 5-element Petzval design, which eliminates the need for backfocus adjustments as it inherently flattens the field, eliminating the need for an external field flattener. This design ensures sharp, edge-to-edge images with pinpoint stars, making it ideal for both wide-field and detailed astrophotography. The telescope has a fast f/4.9 focal ratio, providing excellent light-gathering power and sharp detail even on faint celestial objects.
With a large 50mm image circle, the William Optics WIFD RedCat 91 APO is perfect for both full-frame and medium-format cameras. It contains 2 Super ED and 1 ED glass and lanthanum lenses with advanced fully multi-coatings, delivering sharp, vibrant images with true-to-life colors, significantly reducing chromatic aberration. These advanced optics achieve flat-field images without requiring an additional flattener.
The RedCat 91 is equipped with William Optics’ WIFD (William Optics Integrated Focusing Device) focuser. This system provides precise, stable focusing without additional adjustments, enhancing ease of use for both seasoned astrophotographers and beginners. The focuser includes a built-in tension screw to prevent over-tightening, ensuring smooth and accurate focusing.
The William Optics WIFD RedCat 91 APO includes a built-in tilter to help compensate for tilt in an imaging train. Adjusting this useful accessory is straightforward and requires only the included tools. Start by unthreading and completely removing the tension knob of the camera angle adjuster. Next, unthread the camera angle adjuster’s angle guide ring to expose the tilt adjustment ring. Use the provided hex key set to make adjustments to the tilt. The three adjustment points feature Push-Pull-Push screws and they can be adjusted as needed. Then reinstall the angle guide ring and the tension knob to complete the tilt adjustment process.
The telescope is constructed with a robust all-metal body, ensuring durability and longevity. It features a sleek, black finish that is both aesthetically pleasing and functional. It is designed to be portable, making it easy to transport and set up for astrophotography sessions. The RedCat 91 OTA weighs just 10.41lbs and its total weight is 13.89lbs without counterweights.
The RedCat 91 is compatible with a wide range of accessories, including the William Optics UniGuide 32mm f/3.75 guide scope. This guide scope is designed for precision and ease of use, featuring a high-quality, fully multi-coated 32mm objective lens. The guide scope is lightweight and can be easily attached to the RedCat 91.
The set of red anodized rings comes with large clamp knobs and a combo Synta accessory top rail/handle bar, to connect a guide scope or Wi-Fi Camera Controller. These rings attach to mounts through a hybrid dovetail bar, which features a D-style top plate and V-style dovetail connection, providing excellent compatibility. Included riser blocks offer additional clearance under the scope when using accessories like ZWO’s EAF.
To protect the front of the scope when not in use, a red anodized dust cap with a removable lid is provided. Removing the lid exposes a built-in Bahtinov mask, ensuring instant access to precise focusing. Attaching your accessories is simplified with the included M48 and M54 adapters, which accommodate a wide variety of cameras, from full-frame to dual sensor – medium-format cameras will require an adapter.
Also included is a hex key set for setting up the RedCat 91 and adjusting the tilt. A foam padded soft case is provided to keep everything safe and secure when breaking down and transporting the scope.
You can learn more about the William Optics WIFD RedCat 91 APO here.
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