Canon Patent Application: Canon EF-S 55-250mm

While never as exciting as the latest full frame lens patent applications as we discover, the EF-S system (and closely followed by the EF-M system these days) is the backbone of Canons camera sales.  Thus, while research and development happen on the more exciting areas, work still progresses on the more mundane, yet necessary lenses.

This patent application discusses a lens that is compact, lightweight and highly corrected for axial and normal chromatic abberations.

This lens has a long backfocus and a 13.66mm image radius (image height), so it's an EF-S APS-C lens.

Focal distance      56.81 135.00 241.28 
F number             4.03   5.11   5.88 
Field angle         13.52   5.78   3.24 
Image height        13.66  13.66  13.66 
length of the lens 154.60 192.00 209.61 
BF                  38.74  60.94  75.27 

Japan Patent Application 2018-194772

Canon Patent Application: Organic sensor Canon Patent Application: TS-E or medium format lenses