Canon EOS 80D Review – Dual Pixel CMOS AF technology
For those unfamiliar with the term Dual Pixel CMOS AF, it refers to the 80D’s sensor-based autofocusing system. When the camera is switched over to live view mode, the internal mirror is lifted out of the way of the image sensor, allowing the camera to continuously record the light entering the lens and transmitting the data to the rear screen as a live image. The downside to this process is that without the mirror in place, the camera can no longer utilise the main phase-detection AF system in order to focus automatically. One solution to this problem was to incorporate AF sensors on the face of the image sensor itself. Previously, these AF sensors have been of the contrast-detect variety, which are typically slower and less accurate at locking on to targets than phase detection – especially when tracking moving subjects.
To overcome slow focusing speeds in live view, Canon has developed a Dual Pixel CMOS AF system that supports sensor-based, phase-detection autofocusing. The system works by splitting all the effective pixels on the surface of the sensor into two individual photodiodes – one for left and one for right. Each of these photodiodes can be read separately, allowing faster phase-detection autofocus while simultaneously being used for image capture. The Dual Pixel CMOS AF system is beneficial to both photographers and videographers who’d like to compose and shoot quickly without having to put up with a slow and clumsy autofocus performance.
Improving where the 70D left off, the 80D’s Dual Pixel CMOS AF system now supports Servo AF when shooting still images in live view. This allows the user to select focus on a subject and then track it through the frame all the while the shutter button is half depressed. It’s particularly effective for moving subjects and was used to capture the shot above. The Servo AF mode has successfully maintained focus on the car, which was travelling at 30mph.
