Patents were found for the Canon 300mm f/2.8 IS, Canon 400mm f/2.8 IS, and Canon 500mm f/4 IS lenses.
overview
- [Publication number] P2025114982
- [Release date] 2025-08-06
- [Title of Invention] Optical system and imaging device having the same
- [Application date] 2024-01-25
- [Applicant]
[Identification number] 000001007
[Name] Canon Inc. - To provide an optical system that has high optical performance, a long focal length, and is small and lightweight.
- BACKGROUND ART
[0002]
As an optical system with a long focal length, a so-called telephoto type optical system is known, in which a lens group with positive refractive power is arranged on the object side and a lens group with negative refractive power is arranged on the image side. Telephoto type optical systems are used, for example, in single-focus super telephoto lenses. - [0003]
Generally, when the F-number is constant, the longer the focal length of a lens, the larger the effective diameter of the lens’s light beam. Therefore, particularly in optical systems with long focal lengths, there is a demand for lenses that have a small F-number, are compact and lightweight, and have various aberrations well corrected. - In the optical system of Patent Document 1, the diameter of each lens arranged in the first lens group is large because the air gap formed within the first lens group is narrow. Therefore, it cannot be said that the optical system has sufficiently achieved weight reduction .
- SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an optical system that has high optical performance, a long focal length, and is small and lightweight. - [0092]
Here, the intermediate group M is composed of the second lens group L2 and the third lens group L3, and the second lens group L3 and the third lens group L3 move by different amounts during focusing. By moving two lens groups during focusing, a configuration is achieved that makes it easy to suppress fluctuations in various aberrations that occur during focusing. Furthermore, by constructing the second lens group L2 and the third lens group L3 each using a negative single lens, the weight of the lens groups that move during focusing can be reduced.
Example 1
- Focal length: 387.98
- F-number: 2.91
- Half angle of view: 3.19
- Image height: 21.64
- Total length: 372.01
- Back focus: 38.28
Example 2
- Focal length: 543.19
- F-number: 4.12
- Half angle of view: 2.28
- Image height: 21.64
- Total length: 372.05
- Back focus: 38.30
Example 5
- Focal length: 289.77
- F-number: 2.91
- Half angle of view: 4.27
- Image height: 21.64
- Total length: 240.23
- Back focal length: 37.97
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