Canon filed a patent application for 85mm F1.4, 75mm F1.4, 100mm F1.4 and the 85mm F1.2 for full-size mirrorless cameras, most likely aimed at the RF mount, not the RF-s. The problem the patent is trying to solve is optical quality by offering an optical s ystem with excellent correction.
Applicant: Canon Inc.
Publication number: P2023099386
Application number: P 2022000013
Publication date: 2023-07-13
Title of the invention: Optical system and imaging device having the same
The patent application aims to provide an optical system capable of satisfactorily correcting aberrations over a wide range of object distances while achieving miniaturization of a focus lens group. Satisfactory is obviously a subjective term - satisfactory to pro wildlife photographers, passion photographers or kids playing with their first camera — it doesn't say.
Optical systems have achieved a reduction in the size of the overall lens diameter of the focus lens group. However, in the optical system described in Patent Document 1, when the aperture of the optical system is increased, the focal length of the focus lens group having a positive refractive power and the fourth lens group arranged on the image side of the focus lens group focal length is not set properly. For this reason, in the optical system described in Patent Document 1, it is difficult to suppress aberration fluctuations during focusing when the optical system has a large aperture.
The present invention provides an optical system capable of satisfactorily correcting aberrations over a wide range of object distances while achieving a compact focus lens group.
Example 1: 85mm F1.4
- Focal length 82.50
- F value 1.46
- Half angle of view 14.69
- Image height 21.64
- Total length 112.50
- Back focus 13.00
Example 2: 75mm F1.4
- Focal length 72.10
- F value 1.46
- Half angle of view 16.70
- Image height 21.64
- Total length 108.50
- Back focus 12.99
Example 3: 100mm F1.4
- Focal length 97.50
- F value 1.46
- Half angle of view 12.51
- Image height 21.64
- Total length 125.50
- Back focus 13.00
Example 4: 85mm F1.2
- Focal length 82.50
- F value 1.24
- Half angle of view 14.69
- Image height 21.64
- Total length 135.50
- Back focus 15.03
I sometimes get lost we reviewing patent applications, especially with canon patent application P2022000013 where each of the examples are very similar, slight changes to the lens groupings where the labels remain the same. Then there is translating Japanese to English — it's kind of like going on an Easter egg hunt never knowing what you'll encounter.
Do you find these Canon patent applications useful? Drop us a comment and let us know.
