US20130208155A1, published Aug 15th 2013, has foreign priority data JP20120030668 20120215.
The patent app entails 1 embodiment of an EF 70-200 (72-193) F4 IS and 3 embodiments of an EF200-400 (205-390) F4 IS design. The patent claims that for the inner focusing design used it is important to correctly set refractive powers in order to obtain good aberration variation reduction at all zoom settings, subject distances - in particular for near MFD focus, maintaining a good zoom ration and keeping the lens size small..
Further details here: http://www.freepatentsonline.com/20130208155.pdf
The patent app entails 1 embodiment of an EF 70-200 (72-193) F4 IS and 3 embodiments of an EF200-400 (205-390) F4 IS design. The patent claims that for the inner focusing design used it is important to correctly set refractive powers in order to obtain good aberration variation reduction at all zoom settings, subject distances - in particular for near MFD focus, maintaining a good zoom ration and keeping the lens size small..
Further details here: http://www.freepatentsonline.com/20130208155.pdf
