Canon Patent: 400mm f/4 DO IS Extender 1.4x and 600mm f/4 IS Extender 1.4x

February 7, 2022
Canon Patents
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Drawing from the patent literature

A new Canon patent application was spotted. 400mm f/4 DO IS Extender 1.4x and 600mm f/4 IS Extender 1.4x are discussed.

Canon patent application 2022-22771 discusses optical formulas for two rather interesting lenses:

400mm f/4 DO IS Extender 1.4x
600mm f/4 IS Extender 1.4x

PROBLEM TO BE SOLVED: To provide an optical system in which a magnification conversion optical group can be inserted and removed and the total length is short.
As a method of changing the focal length of the optical system used for imaging, there is a method of inserting a magnification conversion optical group such as an extender into the optical path . Further, as an optical system in which the total length (distance from the optical surface on the object side to the image surface) does not change due to the insertion / removal of the magnification conversion optical group, Patent Document 1 describes the axial light beam between the aperture stop and the image surface. An optical system capable of inserting and removing a magnification conversion group at a converging position is disclosed.
However, if a space for inserting the magnification conversion optical group is provided between the aperture diaphragm and the image plane as in Patent Document 1, the total length of the original optical system becomes long . Further, if the magnification conversion optical group is inserted in a narrow space, various aberrations of the optical system may increase. The
present invention provides an optical system in which a magnification conversion optical group can be inserted and removed, but the total length is short and good optical performance can be obtained.

Example 1

Focal length: 392.58
F value: 4.12
Half angle of view: 3.15
Image height: 21.64
Overall length: 280.33
Back focus: 36.01

Example 1 (with inserted teleconverter)

Focal length: 549.72
F value: 5.77
Half angle of view: 2.25
Image height: 21.64
Overall length: 280.33
Back focus: 36.00

Example 5

Focal length: 585.00
F value: 4.12
Half angle of view: 2.12
Image height: 21.64
Overall length: 467.45
Back focus: 55.50

Example 5 (with inserted teleconverter)

Focal length: 819.18
F value: 5.77
Half angle of view: 1.51
Image height: 21.64
Overall length: 467.45
Back focus: 55.50

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