Canon Patent Application: Fast Focusing Prime lenses

neuroanatomist

Canon Rumors Premium
Jul 21, 2010
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Personally I'm more curious about a patent application mentioning (APS-C?) designs for 10-21mm f/2-2.8 and 11-28mm f/2-2.8 wideangle zooms, though I'm not sure they are meant for consumer RF mount cameras (Richard?):


If it is an APS-C design, the 10-21mm would be an interesting option for me (the other wouldn't be wide enough to replace my current EF-S wideangle zoom).
The patent includes this drawing of one way in which these lens designs could be employed…

IMG_9068.jpeg
 
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Sep 20, 2020
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Personally I'm more curious about a patent application mentioning (APS-C?) designs for 10-21mm f/2-2.8 and 11-28mm f/2-2.8 wideangle zooms, though I'm not sure they are meant for consumer RF mount cameras (Richard?):


If it is an APS-C design, the 10-21mm would be an interesting option for me (the other wouldn't be wide enough to replace my current EF-S wideangle zoom).
Curiously, image height is not mentioned in the patent at all.
It would not need to be for just a design formula but it would mean that it is nowhere close to being an actual lens.
 
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SwissFrank

1N 3 1V 1Ds I II III R R5
Dec 9, 2018
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Just because the back focus is smaller than the flange distance does not necessarily mean the rear element will protrude into the mount.
It necessarily means that.
They can extend the length of the lens a few mm.
The distance from the back of the lens to the sensor is part of the optics design. You can't just move all the glass forward and have it still work. For a start, focus distance normally becomes much closer, but on today's massively corrected lenses, I'd be willing to bet that all sorts of aberrations would be present if you used an extension tube which may be why Canon doesn't offer such a thing now.
 
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