Patents were found for Canon 20-60mm f/2.8 and Canon 28-70mm f/2.8 lenses. These lenses will fit well with Canon’s current RF lineup of lenses.
overview
- [Publication number] P2024074321
- [Release date] 2024-05-31
- [Name of invention] Zoom lens, and optical device and imaging system having the same
- [Application date] 2022-11-21
- [Applicant]
[Identification number] 000001007
[Name or company name] Canon Inc. - A zoom lens that is compatible with a short back focus, has an inexpensive configuration, and exhibits high optical performance over the entire zoom range and all subject distances.
- 2. Description of the Related Art
In recent years, large-aperture zoom lenses that are inexpensive and have high optical performance over the entire zoom range and all subject distances have become attractive in the market. - [0003]
As one technique for improving performance, a so-called floating focus method is known in which a plurality of focus lens groups are moved simultaneously during focusing. - [0004]
In addition, the number of cameras that do not have a quick-return mirror, so-called mirrorless cameras, is increasing. Since these mirrorless cameras do not require the space for a quick-return mirror, there is no need to ensure a back focus as much as in conventional interchangeable lenses. Therefore, the lens configuration also differs from conventional interchangeable lenses, and there is more freedom in design, making it possible to design compact and lightweight lenses. In particular, wide-angle lenses tend to have a short back focus, so they can be made compact as interchangeable lenses for mirrorless cameras. - [0005]
In addition, recent advances in image processing technology have made it possible to electrically correct some aberrations. In particular, by electrically correcting various aberrations such as chromatic aberration and distortion, and by configuring the device to be suitable for correcting other aberrations, it is possible to achieve size reduction, high image quality, and cost reduction. - [0009]
However, the zoom lens disclosed in Patent Document 1 has problems in that the zoom range is short and the F-number at the telephoto end is low. - The present
invention provides a zoom lens that is compatible with a short back focus, has an inexpensive configuration, and has high optical performance over the entire zoom range and all subject distances.
Example 1
- Focal length: 24.70-68.70
- F-number: 2.89
- Half angle of view: 36.73-17.48
- Image height: 171.15-157.34
- Overall length: 171.15-157.34
- Back focus: 22.75-28.19
Example 2
- Focal length: 28.70-68.70
- F-number: 2.89
- Half angle of view: 32.71-17.48
- Overall length: 158.44-153.21
- Back focus: 22.44-26.15
Example 3
- Focal length: 28.70-68.70
- F-number: 4.12
- Half angle of view: 32.71-17.48
- Overall length: 156.82-149.07
- Back focus: 23.82-35.09
Example 4
- Focal length: 21.63-61.25
- F-number: 2.89
- Half angle of view: 39.77-19.45
- Overall length: 171.39-154.91
- Back Focus: 22.99-30.88
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