Canon Patent: RF 16-28mm f/2.8, RF 15-28mm f/2.8-4 and RF 15-28mm f/4-5.6 IS

April 22, 2022
Canon Patents
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A new Canon patent, once again for RF mount lenses. Some interesting lenses, we might add.

Canon patent application 2022063727 (Japan) discusses optical formulas for three RF mount lenses:

RF 16-28mm f/2.8
RF 15-28mm f/2.8-4
RF 15-28mm f/4-5.6 IS

PROBLEM TO BE SOLVED: To provide a zoom lens having a wide angle of view, easy to manufacture, and having little aberration fluctuation due to scaling.
In the zoom lenses disclosed in Patent Documents 1 and 2, in order to satisfactorily correct distortion and curvature of field, aspherical lenses having a large uneven thickness and a large diameter are added to the first lens group and the second lens group. Is used. As a result, it is difficult to manufacture a zoom lens.
The present invention provides a zoom lens capable of satisfactorily correcting distortion and curvature of field while having a wide angle of view and being easy to manufacture.

Example 1

Focal length: 16.45-27.50
F value: 2.88
Half angle of view: 52.71-38.49
Image height: 19.00-21.64
Overall length: 134.57-119.35
Back focus: 14.07

Example 2

Focal length: 15.40-27.50
F value: 2.88-4.04
Half angle of view: 54.50-38.66
Image height: 19.00-21.64
Overall length: 114.50-110.87
Back focus: 14.15

Example 3

Focal length: 15.40-27.50
F value: 4.00-5.60
Half angle of view: 54.51-38.94
Image height: 19.00-21.64
Overall length: 103.50-103.50
Back focus: 14.20

The Canon patent was spotted by Asobinet. More Canon patent applications are listed here. Some particularly interesting patent applications we think might get into production are these: