Example 1 (24-70mm F2.8)
Zoom ratio 2.75 Wide-
angle intermediate telephoto
focal length 24.72 39.76 67.98
F number 2.92 2.92 2.92
Full angle of view 2ω 85.24 56.96 34.33
Image height Y 21.63 21.63 21.63
Lens total length 135.00 145.60 171.09
Back focus 17.6206 17.6036 17.5749
Example 3 (28-70mm F2.8)
Zoom ratio 2.35 Wide-
angle intermediate telephoto
focal length 28.81 40.01 67.69
F number 2.92 2.92 2.92
Full angle of view 2ω 75.92 56.06 33.85
Image height Y 21.63 21.63 21.63
Lens total length 120.04 126.08 142.66
Back focus 19.6292 19.5884 19.6020
Example 4 (28-85mm F2.8)
Zoom ratio 2.90 Wide-
angle intermediate telephoto
focal length 28.79 49.98 83.51
F number 2.92 2.92 2.92
Full angle of view 2ω 75.61 45.42 27.77
Image height Y 21.63 21.63 21.63
Lens total length 135.02 146.97 164.94
Back focus 17.6146 17.5433 17.5817
Applicant: Sigma Co., Ltd.
Publication number: P2022067732
Application number: P 2020176481
Publication date: 2022-05-09 Title
of invention: Large-diameter zoom lens
PROBLEM TO BE SOLVED: To provide a large-diameter zoom lens which includes a standard range in a variable magnification range, has a small open F value, has a compact overall length, and is capable of high-speed autofocus control.
In the conventional example of the zoom lens, the focus lens group is composed of a large number of lenses, and the weight thereof is large. Therefore, in order to enable high-speed autofocus control, the weight reduction of the focus lens group is insufficient.
When the zoom lens disclosed in Patent Document 1 is applied to a camera equipped with a so-called full-size image sensor, the back focus becomes longer and the overall length becomes longer as the entire optical system becomes larger.
The present invention has been made in view of the above problems of the conventional example, and is a large-diameter zoom lens that includes a standard range in a variable magnification range, a small open F value, a compact overall length, and high-speed autofocus control. The purpose is to obtain.
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