Canon introduced its Dual Pixel CMOS Autofocus (AF) technology back in 2013 with the launch of the EOS 70D. It performs phase-detect autofocus from the main imaging sensor by splitting each pixel into two light-sensitive photodiodes, with each half picking up light independently through separate microlenses.
Since then, this system has provided fast and accurate autofocus in Canon’s cameras and is, after all these years, still considered to be one of the most reliable AF technologies for both stills and video.
So imagine the possibilities if those pixels could be divided into four photodiodes. Hopefully we won’t have to wonder for too long, as a patent application, first discovered by Canon News, suggests the camera manufacturer could be working on a Quad Pixel AF system.
Halved, then quartered
The patent, filed in Japan, describes a 20.7MP sensor that contains a staggering 83 million focus detention points. Each pixel seems to be 4 micrometers, making the sensor approximately 22mm wide (the size of an APS-C sensor). According to Canon News, the decreased pixel density is what would make Quad Pixel AF possible, requiring Canon to drop from a 24MP Dual Pixel CMOS sensor to a 20MP Quad Pixel option.
Splitting each pixel into four pieces would solve an issue most Canon cameras have when focusing. “If you ever tried to use an EOS R or an EOS M in landscape orientation to focus on a horizontal line, you’ll quickly realize that the phase detect sensors just go in one direction, and have little sensitivity in the other 90 degrees offset direction,” Canon News explains.
Quad Pixel AF would solve this problem, but the size of the sensor suggests Canon will be restricted to using the new AF system in APS-C cameras. Whether it can be developed for high resolution full-frame systems remains to be seen.