Canon RF 70-200mm f/2.8 L IS USM Z, 200-400mm f/4 and 200-500mm f/5.6 Patents Found

Louis Ferreira

2 days ago

Canon RF 70-200mm f/2.8 L IS USM Z:
B&H Photo / Amazon / Adorama

Patents for a Canon 200-400mm f/4 and 200-500mm f/5.6 have been found, which include the Canon RF 70-200mm f/2.8 L IS USM Z. You can check out the filing below:

overview

[Publication number] P2025080464
[Release date] 2025-05-26
[Name of invention] Zoom lens and imaging device
[Application date] 2023-11-14
[Applicant]
[Identification number] 000001007
[Name or company name] Canon Inc.
To suppress aberration fluctuation and one-sided aperture occurrence that occur during zooming in a small and lightweight zoom lens.
[Background Art]
[0002]
In a zoom lens, the moving lens group is required to be lightweight in order to suppress the change in the center of gravity that accompanies the movement of the lens group during zooming, to reduce the torque required to drive the lens group, etc. Also, during focusing, it is required that the change in the angle of view is small, i.e., focus breathing is small, and the moving lens group (focus group) is lightweight.
[0003]
In a large-aperture telephoto zoom lens, the refractive power of the first lens group, which is the closest to the object, is generally positive. In this case, by fixing the first lens group, which is the heaviest, and adopting rear focusing, it is possible to reduce the weight of the lens groups that move during zooming and focusing. In addition, since the change in the angle of view due to focus breathing is more noticeable when the aperture is narrowed, it is required that focus breathing be small when the aperture is narrowed.
[0004]
However, if the diameter of the first lens group is kept small while ensuring sufficient peripheral light volume in order to achieve a compact and lightweight zoom lens, the chief ray of the peripheral light flux is likely to shift from the center of the aperture, resulting in a so-called one-sided aperture state. If the aperture is narrowed in a one-sided aperture state, focus breathing due to the movement of the lens group on the image side of the aperture tends to increase. In addition, even if the aperture is opened, the amount of light is unlikely to increase, and the blurred image becomes asymmetrical.
The present
invention provides a zoom lens which is small and lightweight, yet has high optical performance over the entire zoom range and the entire focus range by suppressing the occurrence of aberration fluctuations and one-sided aperture caused by zooming.