William Optics RedCat 91: First Look

In this video, we unbox our William Optics Cat 91 WIFD telescope, discuss its specs, and use spot diagrams to illustrate its amazingly flat field. Its spots are smaller than the Cat 71 and the Takahashi FSQ-106EDX4, and are just barely larger than the Airy disc, meaning that the Cat 91 has effectively diffraction-limited optics.

The associated short video can be found here:
   • William Optics RedCat 91: First Look ...  

Photos and spot diagrams for these telescopes were obtained from the manufacturer websites:
https://williamoptics.com/products/ca...
https://williamoptics.com/products/ca...
https://takahashi-europe.com/catalog/...