Canon patent application offers solution for Live View autofocus issues
Canon's Live View implementation may not be a deal-breaker for most DSLR users, but there's certainly plenty of room for improvement, and a recent Canon patent application suggests that the company could possibly be aiming to do just that. The short of it is that the company seems to have found a way to overcome the inherent problems of employing so-called phase-difference autofocus in Live View, which is caused in part by the physical limitations of the mirror and the AF sensor (hit up the read link for some more background). Canon's solution, it seems, is to place the phase-difference AF sensor below the image sensor instead of above it, and make use of a semi-transparent mirror that'd allow for simultaneous transfer of light to the image sensor and the AF sensor. The average user would see the changes in the form of three new shooting modes, including a Standard Viewfinder Mode, a Fast AF Live View Mode, and a Full Live View mode, which each shift the position of the mirrors for the task at hand. What's more, while the patent application doesn't address it specifically, it would seem that this same method could also bring autofocus to DSLR video or, at the very least, video recorded via Live View.
