Canon Patent: 70-150mm f/2 and 70-200mm f/2.8 With Inner Zoom

December 13, 2023
Canon Patents
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Here is a new Canon patent application, two lenses with inner zoom mechanism.

Canon patent application 2023176289 (Japan, published 12/13/2023) discusses optical formulas and methods for two zoome lenses with a not extending zoom mechanism:

70-150mm f/2
70-200mm f/2.8

From the patent literature:

An object of the present invention is to provide a zoom lens that has a long focal length and a large aperture ratio, yet is both compact and lightweight and has high optical performance.
BACKGROUND ART
Zoom lenses used in imaging devices are required to be small and lightweight, to satisfactorily correct various aberrations including chromatic aberration, and to have high optical performance. Furthermore, zoom lenses are required to have a long focal length at the telephoto end, a small F number, and a large aperture ratio. Furthermore, zoom lenses are required to have a large zoom ratio and be easy to manufacture.
However, the zoom lens described in Patent Document 1 tends to have large aberrations including chromatic aberration, making it difficult to have high optical performance. If the power of the lens groups making up the zoom lens is weakened in order to better correct the aberrations, the zoom lens will become larger. Furthermore, if aberrations are corrected by increasing the number of lens groups that make up the zoom lens, the mechanical mechanism will become complicated and the zoom lens will become larger.
The present invention provides a zoom lens that has a long focal length and a large aperture ratio, yet is both compact and lightweight and has high optical performance.

Example 1