Canon patent application offers solution for Live View autofocus issues at DVinfo.net

Nicholas de Kock · February 11th, 2009, 04:04 PM

Canon patent application offers solution for Live View autofocus issues - Engadget

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.

Jon Fairhurst · February 11th, 2009, 04:41 PM

Very interesting.

I wonder how autofocus is implemented in video cameras today? Obviously, they don't have mirrors. I would guess that the key technology is the control loop that balances speed for smoothness.

Maybe the new technology will improve on the speed and accuracy of autofocus in normal camcorders.

Nicholas de Kock · February 11th, 2009, 05:40 PM

Things can only get better for us, holding thumbs.

February 11th, 2009, 04:04 PM	#1
Nicholas de Kock Major Player Join Date: May 2007 Location: KLD, South Africa Posts: 983	Canon patent application offers solution for Live View autofocus issues Canon patent application offers solution for Live View autofocus issues - Engadget 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.

February 11th, 2009, 04:41 PM	#2
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Very interesting. I wonder how autofocus is implemented in video cameras today? Obviously, they don't have mirrors. I would guess that the key technology is the control loop that balances speed for smoothness. Maybe the new technology will improve on the speed and accuracy of autofocus in normal camcorders. __________________ Jon Fairhurst

February 11th, 2009, 05:40 PM	#3
Nicholas de Kock Major Player Join Date: May 2007 Location: KLD, South Africa Posts: 983	Things can only get better for us, holding thumbs.