Canon Patent: 16mm f/2.8 & 20mm f/2.8 With Image Stabilization

October 3, 2022
Canon Patents
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Drawing from the patent literature

A new Canon patent to start a new week. Once more for lenses for the RF mount.

Canon patent 2022125455 (Japan, published 8/29/2022) discusses optical formulas for two prime lenses, a 16mm f/2.8 and a 20mm f/2.8, both with image stabilisation. From the patent literature (machine translated):

[Title of Invention] Optical system, lens device having the same, and imaging device
The present invention provides an optical system having a wide angle of view, a small size and light weight, and high optical performance in the non-stabilizing state while suppressing peripheral image quality deterioration during image blur correction, and a lens device and an imaging device having the same.
Description of the Related Art
Conventionally, as means for correcting image blurring, there are known a lens-shift type anti-vibration mechanism that shifts a part of an optical system and a sensor-shift type anti-vibration mechanism that shifts an imaging device. In a central projection optical system, the amount of movement of the image point in response to changes in the angle of incidence of light rays entering the optical system is not uniform on the imaging surface. However, image blur remains around the imaging surface.
The imaging apparatus of Patent Document 1 can correct image blur at a specific image point position, but cannot uniformly correct image blur at all angles of view.
In an equidistant projection optical system, the image quality around the imaging surface is less likely to deteriorate during image blur correction. Therefore, in order to suppress image quality deterioration around the imaging surface, it is necessary to generate a large amount of distortion in the negative direction in the central projection method, and reduce the absolute value of the amount of distortion in the equidistant projection method.
An optical system with a large absolute value of the amount of distortion aberration in the central projection method produces a greatly distorted image, so it is often used in combination with an imaging apparatus equipped with electronic distortion correction. In this case, if the distortion aberration in the central projection method is excessively generated, the image quality around the imaging surface is degraded due to the extension of the electronic distortion correction.

Example 1