Canon Patent Application: Catadioptric IS Super telephotos

Canon at times dabbles with various things in their patent applications, this is one that is interesting, and may also be a very cheap super telephoto option, but I doubt it will ever be taken seriously.  You see these lenses on ebay and also amazon, and they are super cheap.  But these lenses are good for basically one thing; infinity focus. Outside of infinity focus, you have donut shaped bokeh, which is unavoidable, because the entry of light is obscured by the secondary mirror at the front of the lens.  This central obscuration is a key trait of a Catadioptric lens. 

But, every lens is a compromise, and this, while certainly has compromises, gives a very long telephoto option that is VERY small and much lighter than a normal lens.

The interesting part of these embodiments is the fact that Canon is adding image stabilization to the lenses.  This has never been done before.

It's impossible to suggest that these lenses are either EF or RF, they could be either because the back focus distance is considerably large with the embodiments.

Canon 1200mm F11

Focal Length        1199.87
F-Number              10.58
Half Angle of view     1.03
Image height          21.64
Overall Lens Lenght  275.87
Back Focus           123.44

Canon 400mm F3.5 

Focal Length         399.12
F-Number               3.57
Half Angle of view     3.10
Image height          21.64
Overall Lens Lenght  206.85
Back Focus            59.29

Canon 2000mm F15 

Focal Length        1999.72
F-Number              15.00
Half Angle of view     0.62
Image height          21.64
Overall Lens Lenght  331.40
Back Focus            93.81

US Patent Application 20210141240

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