Canon filed a patent for Fish Eye 8-15mm F4, 16mm F2.5, and 17mm F2.5 lenses.
overview
- [Publication number] JP2025-12993 (P2025-12993A)
- [Release date] January 24, 2025 (2025.1.24)
- [Name of invention] Lens device and imaging device
- [Application date] July 14, 2023 (2023.7.14)
- [Applicant]
[Identification number] 000001007
[Name or company name] Canon Inc. - By adding another optical system to a master optical system, distortion is suppressed while avoiding an increase in the size of the entire optical system.
- 2. Description of the Related Art
[0002]
As a method for obtaining a wide-angle lens with low distortion from a fisheye lens, Patent Document 1 discloses a method for converting the projection method of a fisheye lens to a general projection method by placing an aspherical dome-shaped lens with negative refractive power on the object side of the fisheye lens (master optical system). Patent Document 2 discloses a method for changing the projection method by exchanging an intermediate portion between the object side and image side of the optical system. - Placing a dome lens on the object side of a fisheye lens as in Patent Document 1 leads to an increase in size of the entire optical system. Furthermore
, the method of replacing an intermediate part of the optical system as in Patent Document 2 requires replacement work and the configuration to enable replacement becomes complicated. - The present invention
provides a lens device that can suppress distortion while avoiding an increase in the size of the entire optical system by adding another optical system to the master optical system.
Example 1-A
- Focal length: 8.25-15.48
- F-number: 4.12
- Half angle of view: 53.50-54.42
- Image height: 11.15-21.64
- Overall length: 105.00
- Back focus: 25.50-40.85
Example 1-B
- Focal length: 15.41
- F-number: 4.12
- Half angle of view: 54.54
- Image height: 21.64
- Overall length: 105.00
- Back Focus: 18.25
Example 3-A
- Focal length: 16.11
- F-number: 2.50
- Half angle of view: 53.33
- Image height: 21.64
- Overall length: 81.19
- Back focal length: 22.76
Example 3-B
- Focal length: 18.69
- F-number: 2.90
- Half angle of view: 49.17
- Image height: 21.64
- Overall length: 88.32
- Back focal length: 9.91
Example 4-A
- Focal length: 17.67
- F-number: 2.50
- Half angle of view: 50.76
- Image height: 21.64
- Overall length: 100.05
- Back Focus: 41.09
Example 4-B
- Focal length: 16.71
- F-number: 2.36
- Half angle of view: 52.32
- Image height: 21.64
- Overall length: 100.06
- Back focal length: 9.61
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