Canon filed patents for a Canon 28-105mm F4 and 24-35mm F2 lens that you can read below:
overview
- [Publication number] P2025019790
- [Release date] 2025-02-07
- [Name of invention] Zoom lens and imaging device
- [Application date] 2023-07-28
- [Applicant]
[Identification number] 000001007
[Name or company name] Canon Inc. - [Background Art]
[0002]
In order to realize a small-sized, large-aperture zoom lens with well-corrected aberrations, it is preferable to arrange an aspherical lens with strong refractive power in a lens group near an aperture stop through which a large diameter of light passes. In addition, in order to reduce the weight of the zoom lens, it is preferable to use a resin material as the lens material. - [0003]
However, the shape and refractive index of resin lenses change significantly with temperature changes, which can easily cause fluctuations in the focal position and aberration. Patent Document 1 discloses a zoom lens in which a resin lens with positive refractive power and a resin lens with negative refractive power are arranged in the same lens group, so that fluctuations in the focal position and aberration caused by temperature changes are cancelled out between the resin lenses. - [0004]
In addition, generally, high-dispersion resin materials have a high water absorption rate, and the shape and refractive index change significantly with changes in humidity. Therefore, when a high-dispersion material is used for a resin lens, such as the zoom lens of Patent Document 1, the fluctuations in the focus position and aberration due to moisture absorption are large, and it is necessary to suppress this. However, since it takes a long time for the characteristics of a moisture-absorbed resin lens to stabilize and the degree of moisture absorption varies from resin lens to resin lens, it is difficult to predict the fluctuations in the focus position and aberration due to changes in humidity, and it is difficult to cancel out the fluctuations between resin lenses. Patent Document 2 discloses a method of weakening the refractive power of a resin lens using a high-dispersion material as a method of suppressing the fluctuations in the focus position and aberration due to changes in humidity. - The
present invention provides a small, lightweight zoom lens that uses a resin lens and is capable of suppressing degradation of optical performance due to changes in temperature and humidity.
Example 1
- Focal length: 24.70-48.80
- F-number: 2.90
- Half angle of view: 37.93-23.91
- Image height: 19.25-21.64
- Total length: 127.00-146.40
- Back focus: 19.97-29.15
Example 3
- Focal length: 24.70-67.90
- F-number: 2.90
- Half angle of view: 37.63-17.67
- Image height: 19.04-21.64
- Total length: 141.13-173.50
- Back focus: 13.00-31.83
Example 4
- Focal length: 28.84-101.85
- F-number: 4.12
- Half angle of view: 33.94-11.99
- Image height: 19.41-21.64
- Overall length: 185.56-248.11
- Back focus: 19.76-23.79
Example 5
- Focal length: 24.70-33.95
- F-number: 2.06
- Half angle of view: 37.63-31.36
- Image height: 19.04-20.69
- Overall length: 142.44-130.51
- Back focus: 13.00-18.74
Example 6
- Focal length: 24.70-33.95
- F-number: 3.61
- Half angle of view: 37.62-31.76
- Image height: 19.04-21.02
- Overall length: 117.52-107.27
- Back focus: 13.12-12.12
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