Patent application for optical systems such as Sigma “18-50mm F2.8-4 OS” and “17-40mm F4 OS”
Overview
- [Public number] P2022158386
- [Release date] 2022-10-17
- [Title of Invention] Imaging Optical System
- [Application date] 2021-04-02
- [Applicant]
[Identification number] 000131326
[Name] Sigma Corporation - Kind Code: A1 A compact image forming optical system having a small open F value over the entire zoom range is provided.
- 2. Description of the Related Art
In recent years, a so-called mirrorless camera, which eliminates a quick-return mirror that is arranged between an imaging optical system and an imaging device and guides light rays to a finder optical system, has become popular. Since the body of the mirrorless camera has been downsized by eliminating the mirror, downsizing of the imaging optical system is required accordingly. There is also a demand for a large-aperture zoom lens with a small open F value over the entire zoom range. - [0004]
Patent Document 1 discloses a bright positive lead type zoom lens with an open F number of about 2.8. However, there is a problem that the size of the imaging optical system is large. Also, in Patent Document 2, his zoom lens of positive lead type with a miniaturized imaging optical system is disclosed. However, there is a problem that the open F-number at the telephoto end is about 6.3, which is dark.
Example 1
- Focal length: 18.60-48.50
- F-value: 2.92
- Half angle of view: 79.04-31.24
- Image height: 14.20
- Overall length: 91.81-114.15
Example 6
- Focal length: 18.43-53.40
- F-value: 2.91-4.00
- Half angle of view: 80.50-28.42
- Image height: 14.20
- Total length: 85.00-110.00
Example 7
- Focal length: 16.30-38.99
- F-value: 2.91
- Half angle of view: 87.23-38.26
- Image height: 14.20
- Overall length: 85.01-106.84
Example 8
- Focal length: 17.45-48.50
- F-value: 4.11
- Half angle of view: 83.61-31.16
- Image height: 14.20
- Overall length: 80.01-105.10
Example 9
- Focal length: 23.45-68.00
- F-value: 2.91
- Half angle of view: 63.7-22.74
- Image height: 14.20
- Total length: 115.01-144.79
Example 10
- Focal length: 28.50-72.80
- F-value: 2.92
- Half angle of view: 79.08-31.60
- Image height: 21.63
- Overall length: 135.24-165.37
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