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Product Description
RedCat 91 Optical Design
The William Optics RedCat 91 is the even bigger brother to the highly-regarded RedCat 51 and RedCat 71, which has been raved about by astrophotographers since its release. Building on its siblings' success, the RedCat 91 keeps the same f/4.9 focal ratio and Petzval optical design. This optical design uses five lens elements instead of the three found in triplet refractors. By incorporating this extra elements, the RedCat 91 is able to achieve a flat field without the need for an additional field flattener.
RedCat 91 Image Circle & Camera Compatibility
The flat field image circle on the WO RedCat 91 is over 50mm in diameter, meaning it can provide round stars to the corners on a full frame camera, not something many telescopes can claim in this price range. The RedCat 91 telescope comes with a 48mm/54mm thread on the back, meaning you can easily attach any dedicated astronomy camera with a standard M48x0.75 connection such as ZWO. For DSLR and mirrorless users, simply add an M48 t-ring for your camera type and you'll be ready to do astrophotography right out of the box.
Game-Changing WIFD Focuser
This telescope features William Optics' new patented WIFD focuser. This game-changing design allows the telescope to focus by moving lens elements internally instead of externally. This has numerous benefits, including reducing vignetting, focuser sag, and most importantly, sensor tilt. The WIFD focuser is also compatible with the ZWO EAF out of the box.
Includes William Optics Slide-Base UniGuide 32mm Scope
The 32 mm UniGuide guide scope from William Optics has a focal length of 120 mm and a focal ratio of f/3.75. The guide scope comes with a Vixen-style slide-base. This base is compatible with the William Optics saddle carry handle and the Cat Handle bar (neither handles are included).
The back of the William Optics 32mm UniGuide scope comes with an M42 thread for attaching 1.25" cylindrical-type guide cameras such as QHY, SBIG, and ZWO cameras. Tightening knobs will ensure a stable fit for the attached guiding equipment.
- Aperture: 32mm
- Focal length: 120mm
- Focal ratio: f/3.75
- Length: 265mm
- Weight: 240g
- Available Back Focus: 20.1mm
What can I see with a William Optics RedCat 91 WFID APO Petzval OTA (L-RC91)?
Here are some simulated views of common objects. Results with your telescope will vary with viewing conditions, obrits, equipment and more.
Jupiter with
25mm Eyepiece - 14x Magnification
(Sold Separately)
Jupiter with
10mm Eyepiece - 35x Magnification
Sold Separately
Jupiter with
5mm Eyepiece - 70x Magnification
Sold Separately
Moon with 25mm Eyepiece
14x Magnification
(Sold Separately)
Moon with 10mm Eyepiece
35x Magnification
Sold Separately
Moon with 5mm Eyepiece
70x Magnification
Sold Separately
Andromeda with 36mm Eyepiece
10x Magnification
Sold Separately
Andromeda with 25mm Eyepiece
14x Magnification
(Sold Separately)
Andromeda with 10mm Eyepiece
35x Magnification
Sold Separately
What's in the Box
Specifications
| Focal Length: | 448mm |
| Diameter: | 91mm |
| Aperture: | f/4.9 |
| Focuser: | WIFD (WilliamOptics Internal Focus Design) |
| Image Circle: | 45mm Full Frame |
| Tube Length: | 556mm |
| Tube Weight: | 10.41 lbs |
| Total Weight: | 13.89 lbs |
Spot Diagram
