Canon releases intriguing white paper on radical Dual Pixel CMOS autofocus system


posted Friday, July 26, 2013 at 1:47 PM EDT


Perhaps the biggest new feature in the Canon 70D is its radical new autofocus system, which promises to dramatically improve AF speeds, especially while in Live View and for shooting video. Our initial impression of the system is that it's a significant step above other systems currently available in SLRs. But if you want more information and a look at the background of the project, Canon has released an intriguing white paper about its development.

The paper includes interviews with the R&D team behind the new focusing system, and there are some pretty interesting and bold claims about the Dual Pixel CMOS AF. Multiple times, Canon's R&D team states that even though it's a dramatic change to the sensor itself, there's no loss of imaging functionality or performance. 

Canon also put a huge amount of time and effort into tweaking the new algorithms for use with the company's extensive back catalog of lenses — they spent around half a year testing 103 lenses to make sure they all worked perfectly.

Product Testing Chief Kazuo Nakagawa: “First we started by shooting a predetermined subject, then testing the focus shift. This work was to confirm that it conformed to Canon’s established standards. Of course we confirmed through simulations that focus was achieved with Dual Pixel CMOS AF, however, there were some cases where it did not go that way during actual testing. With old lenses in particular, as this was technology that was not envisioned at the time, disagreements with the simulations were more apt to occur. So, it was necessary to check them all. With the labor of checking the zoom positions for 30 minutes to an hour for each lens, when checking 50 lenses for example, if a problem occurred with the 50th lens and the algorithm needed to be revised, there were cases where all 50 of the lenses would need to checked all over again. From the start of testing, it took about half a year to finish 103 lenses.”

In fact, the system is so fast that Canon had to slow it down slightly while shooting in video mode, to give smoother, less jarring transitions.

If you're at all interested in how this new AF system might work, and the way Canon put it together, the white paper is definitely worth a read.