Canon’s work on super telephoto lenses continues, and we expect to see a few more announced next year ahead of the Summer Olympics which take place in Tokyo, Japan.
Canon’s latest super telephoto lenses the EF 400mm f/2.8L IS III USM and EF 600mm f/4L IS III USM are the lightest such lenses currently available and have begun shipping in small numbers.
USPTO patents 20190041606 and 20190041605 uncovered by Canon News describe the following embodiments.
Canon 300mm f/2.8L IS III USM
Focal length: 294.00mm
Half angle of view: 4.21°
Image height: 21.64mm
Total lens length: 276.40mm