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Canon Patent Application for a 11-440mm f/2.1-4.1 Cinema Zoom lens

Canon Patent Application For A 11-440mm F/2.1-4.1 Cinema Zoom Lens

Canon patent application (US 20180143412) for what looks like a 11-440mm f/2.1-4.1 Cinema Zoom lens.

From the patent literature:

Conventionally, four-unit zoom lenses are often used as zoom lenses for television cameras because it is relatively easy to achieve a wide angle of view, a high zoom ratio, and size and weight reduction. Such a four-unit zoom lens includes, in order from the object side, a first lens unit having a positive refractive power that does not move for zooming, a second lens unit having a negative refractive power that moves during zooming, a third lens unit for correcting variation in the image plane caused by zooming, and a fourth lens unit having a positive refractive power for imaging.

In recent years, there have been proposed zoom lenses for television cameras including three, four, or more movable units as zooming units with functions as a variator and a compensator.

[…]

Thus, the present invention has an objective to provide a zoom lens including three or more movable units as its zooming units and simultaneously achieving a wide angle of view, a high zooming ratio, size and weight reduction, and particularly high performance in the focal length range from the wide-angle end to the zoom middle position. The present invention also aims to provide an image pickup apparatus having such a zoom lens.

To attain the above objective, a zoom lens according to the present invention includes, in order from an object side to an image side, a first lens unit having a positive refractive power that does not move for zooming, a second lens unit having a negative refractive power that moves during zooming, a third lens unit having a negative refractive power that moves during zooming, a fourth lens unit having a negative refractive power that moves during zooming, and a relay lens unit having a positive refractive power and being located closest to the image side that does not move for zooming. The second lens unit moves to the image side from a wide-angle end to a telephoto end. When a focal length fx determined based on a focal length fw of the zoom lens at the wide-angle end and a zoom ratio Z is fx=fw×Z0.38, the zoom lens satisfies 0.05<L2min/L2w<0.98, where L2min is a minimum distance between the second lens unit and the third lens unit in a zoom range from the wide-angle end to the focal length fx, and L2w is a distance between the second lens unit and the third lens unit at the wide-angle end.

Patent literature is a hard reading. If I got it wrong or if you have additional intel, please feel free to sound off in the comment section.

canon patent application

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