Atypically in patent embodiments, it’s usually difficult for super-telephoto zoom lens to take full advantage of the RF mount.
One reason is that you simply can’t use a Tele extender if the rear elements are sitting too far back in the lens. Because of this, at times, it’s difficult to determine if a patent application is for RF or EF lenses because there’s so much room in the rear of the lens from the last element to the sensor plane, that it could be either mount type.
In this Japan Patent application, 2022-053697, Canon is applying for some higher magnification (shorter MFD) super-telephoto zooms.
These embodiments show a back focus distance of around 30mm, which would make them more extender non-friendly for the entire zoom range. But they could fit the extender on for only the telephoto part of their zoom, similar to the RF 100-500L. With a short back focus distance, these embodiments are certainly RF mount only.
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