Canon Patent Application: An improved EF-M 15-45mm
The current EF-M 15-45 is a mixed bag for performance. it's entirely possible to get a good copy of this lens, but usually, one is stuck with a lesser performing lens.
This is yet another patent application for an EF-M 15-45. We have seen a few of these patent applications, so it's obvious that even Canon isn't too terribly impressed with the current design.
This one appears to contain 12 elements versus 10 elements in the current EF-M 15-45, with hopefully the more complex element design leading to improved performance. What Canon is looking at is improved AF performance, leading to improved optical performance with this lens.
The zoom lens used for an imaging device is a wide field angle, and the whole lens system's being small and a focus lens group can perform focusing at high speed by a small light weight, and, moreover, it is strongly requested on the occasion of focusing that there are few aberration variations etc. In order to make a focus lens group into a small light weight, it is necessary to lessen the composed lens number of sheets of a focus lens group. However, when the composed lens number of sheets of a focus lens group is lessened, the residual aberration of a focus lens group enlarges. For this reason, an aberration variation enlarges on the occasion of focusing, and it becomes difficult to obtain optical performance with a good rear spring supporter from a long distance to the object distance at large [ to a short distance ]
Japan Patent Application 2018169618
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