Canon Patent: 70-200mm f/2.8 With Inner Zoom Mechanism

August 30, 2024
Canon News
0 Comments

Here is a new Canon patent application. Canon patent 2024117881 (Japan, published 8/30/2024) discusses optical formulas for a70-200mm f/2.8 lens with long back focus and internal zoom extension.

From the patent literature:

A positive-lead zoom lens system is provided that has high optical performance over the entire zoom range while being compact in size.
Description of the Related Art: In recent years, imaging optical systems used in imaging devices are desirably compact zoom lenses that have high optical performance over the entire zoom range.
Conventionally, there have been proposed positive-lead type zoom lenses in which a lens group with positive refractive power is disposed closest to the object side. Patent Document 1 discloses a positive-lead type telephoto zoom lens that is composed of, in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including a plurality of lens groups.
However, in a positive-lead zoom lens, if the refractive power of the lens group with positive refractive power located closest to the object side is increased in order to reduce the size of the entire system, various aberrations such as spherical aberration, chromatic aberration, etc. In order to reduce these various aberrations, it is important to appropriately set the refractive power of each lens group and the lenses contained in each lens group.
The present invention provides a positive lead type zoom lens having a small overall system size and high optical performance over the entire zoom range.

Example 1