Canon Japan has filed a new lens patent for EF 300mm f/2.8L IS USM lens. According to previous rumors, new version of EF 300mm f/2.8L IS USM lens is coming soon. And will be featured with weight and size reduced.
Patent Publication No. 2016-173439
Filing date 2015.3.17
Focal length 292.46
Angle of view 4.23
Image height 21.64
Overall length of the lens 273.95