Canon Patent: 10-18mm f/4.5-6.3 and 10-20mm f/4 (with internal zoom)

Canon patent application 2024007656 (Japan, published 19/01/2024) discusses optical formulas for two wide angle zoom lenses.

From the patent literature:

An object of the present invention is to provide a zoom lens that has high optical performance, is compact, and has a wide angle of view.
BACKGROUND ART
Wide-angle lenses are widely used for landscape photography, astronomical photography, and the like. Wide-angle lenses are required to have high optical performance and realize a wide angle of view while being compact.
Generally, in a negative read optical system, the constituent lens groups are arranged asymmetrically, making it difficult to correct various aberrations such as astigmatism. In particular, when widening the angle of view or downsizing the lens, the refractive power of the lens group closest to the object, which has a negative refractive power, becomes stronger, so that many of the above-mentioned aberrations occur.
For this reason, in order to achieve a wide angle of view and miniaturization in a negative lead type optical system, and to properly correct various aberrations such as curvature of field and obtain high optical performance, the refractive power of each lens group must be adjusted. It is important to set these appropriately.
In Patent Document 1, various aberrations such as astigmatism and field curvature are corrected by weakening the refractive power of each lens group, but this increases the size of the optical system, which is undesirable.
Accordingly, an object of the present invention is to provide a zoom lens that has high optical performance, is small in size, and has a wide angle of view.

Example 1