Canon Patent: RF-S 15-45mm F3.5-6.3 Lens For APS-C Imaging Sensors

And here is another Canon patent application for the RF-S mount. Canon patent 2023182958 (Japan, published 2023-12-27) discusses optical formulas for a lens for the RF-S mount, 15-45mm F3.5-6.3.

From the patent literature:

• An object of the present invention is to provide a zoom lens with good optical performance over the entire zoom range.
• [Background Art] Conventionally, a lens has a first lens group with a negative refractive power and a second lens group with a positive refractive power, which are arranged in order from the object side to the image side, and includes a focal length in the standard range. Zoom lenses are known (see Patent Documents 1 and 2).
• However, in the zoom lens disclosed in Patent Document 1, the entire lens system is large and it is not possible to achieve sufficiently high image quality. Furthermore, in the zoom lens disclosed in Patent Document 2, various aberrations such as spherical aberration and coma aberration are not sufficiently corrected.
• An object of the present invention is to provide a zoom lens with good optical performance over the entire zoom range.

Example 1

• Focal length: 15.36-43.10
• F value: 3.60-6.44
• Half angle of view: 35.76-17.59
• Total length: 76.36-73.51
• Back focus: 10.45

Example 2

• Focal length: 18.45-43.10
• F value: 4.10-6.44
• Half angle of view: 31.58-17.59
• Total length: 80.15-79.38
• Back focus: 13.47-33.69

Example 3

• Focal length: 16.23-43.10
• F value: 3.61-6.44
• Half angle of view: 32.27-17.59
• Total length: 88.10-88.68
• Back focus: 10.87

[via asobinet]