Canon Patent: 400mm F2.8, 500mm F4 And 600mm F4 Lenses

January 19, 2024
Canon Patents
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New Canon patent for you, ladies and gentlemen. Canon patent application 2024009238 (Japan, published 01/19/2024) discusses optical formulas for three telephoto prime lenses, all for fullframe mirrorless cameras.

400mm F2.8
500mm F4
600mm F4

From the patent literature:

[Problem] To obtain an optical system that is lightweight and in which aberrations such as chromatic aberration are well corrected.
[ Background Art] As a photographing optical system with a long focal length, a so-called telephoto type photographing system has an optical system with positive refractive power on the object side and an optical system with negative refractive power on the image side. optical system is known. A telephoto type photographing optical system is used, for example, in a single focus super telephoto lens.
In a super telephoto lens, generally, as the focal length becomes longer, axial chromatic aberration and lateral chromatic aberration occur more frequently. As a method for properly correcting these chromatic aberrations, it is known to increase the number of lenses arranged on the object side and have each lens share the function of correcting the chromatic aberrations. However, a lens placed on the object side of a super-telephoto lens tends to have a large effective diameter, and if the above-mentioned method is used to correct chromatic aberration, the weight of the photographic optical system increases.
In the photographing optical system of Patent Document 1, by arranging a positive lens made of a material having low dispersion and anomalous dispersion continuously from the object side, longitudinal chromatic aberration and lateral chromatic aberration can be corrected. I’m trying.
In order to further reduce the weight of the optical system, it is important to find an appropriate material and arrangement not only for the positive lens but also for the negative lens.
An object of the present invention is to provide an optical system that is compact and in which aberrations such as chromatic aberration are well corrected, and an imaging device having the same.

Example 1