Canon applies for a fisheye lens (one possible mirrorless prime?) patent

We discovered this patent, and while the full frame lens of a 15/4.0 sounds actually quite nice, there is an APS-C lens with a shorter than EF-S backfocus that would also have mirrorless implications.

Edit: as someone noted, these are 175 degrees so most likely prime fisheye lenses.

APS-C 9.5mm 4.0

Focal distance 9.50 
F number 4.10 
Imaging field angle (degree) 175 
Image height 13.66 
Whole length of the lens 63.97 
BF 23.16

Full frame EF mount 15mm 4.0

Focal distance 15.18 
F number 4.12 
Imaging field angle (degree) 175 
Image height 21.64 
Whole length of the lens 130.16 
BF 58.19

Japan Patent Application 2018-004726

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