Digicame-info found some interesting wide-angle Sigma zoom lens patents that are f/1.8. The Sigma 15-24mm f/1.8, 16-28mm f/1.8, and 18-30mm f/1.8 could all be useful zooms, but they will likely be very expensive given their fast apeture.
- Applicant: Sigma Co., Ltd.
Publication number: P2022126058
Application number: P 2021023909
Publication date: 2022-08-30Title
of invention: Zoom lens - A large aperture wide-angle zoom lens capable of high-speed AF control, suppressing aberration fluctuations during focusing, and compatible with a large format camera is provided with a compact optical system.
- The zoom lens described in Patent Document 1 achieves weight reduction of the focus group. However, it is difficult to apply to a large-aperture zoom lens because of its dark open F-number and insufficient correction of various aberrations such as longitudinal chromatic aberration and curvature of field.
- The zoom lens described in Patent Document 2 achieves weight reduction of the focus group and improves longitudinal chromatic aberration and curvature of field as compared with Patent Document 1. However, since the total length of the optical system is long, it is not realistic to make the optical system extremely large if it is to be used with a large-aperture camera or a large-format camera with a large maximum image height.
- According to the present invention, the optical system is made compact by shortening the overall length and reducing the outer diameter. The focus lens group is light, and high-speed AF control is possible. It is possible to provide a large-aperture, wide-angle zoom lens that can be used with any camera and has high optical performance.
- 実施例1（17-28mm F1.8）ズーム比
1.54焦点距離
17.55 21.66 27.10
Fナンバー 1.86 1.86 1.86
全画角 105.33 89.54 74.48像高
21.63 21.63 21.63
レンズ全長 158.61 150.53 144.72バックフォーカス
24.7396 27.5879 30.5018
- 実施例4（18-30mm F1.8）ズーム
比 1.57
焦点距離 18.50 23.38 29.10
Fナンバー 1.86 1.86 1.86
全画角 102.72 85.20 70.59像高
21.63 21.63 21.63
レンズ全長 161.98 154.83 150.90バックフォーカス
24.8386 27.2225 29.4450
- Example 5 (15-24mm F1.8)
Zoom ratio 1.51
Focus distance 15.97 23.30
F Number 1.86 1.86 1.86
Full angle 113.73 83.73 83.24
Image height 21.63 21.63 21.63
Lens total length 159.50 15.020 1510 104.76
Back FOCSHOFOC FOKSD1020101010101010 154
- Example 7 (16-28mm F1.8)
Zoom ratio 1.64
Focusing distance 16.50 21.11 27.10
F Number 1.86 1.86 1.86
Full angle 109.30 91.25 74.48
Image height 21.63 21.63 21.63
Lens length 161.94 157.76
Back Focus 24.76 Back Focus 246.76 Back Focus 246.76 Back Focus 246.76 Buck Focus 246.76 Buck Focus 246.76 Buck Focus 24.76 Buckfork 16
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