Dual Pixel CMOS AF

Dual Pixel CMOS AF
Overview Benefits Technology Videos Compatible Lenses
Shoot Video Like a Camcorder

Dual Pixel CMOS AF represents a rethinking of how to achieve and maintain focus in Live View. Since the camera's mirror is up during Live View shooting, the viewfinder's conventional phase-difference detection AF cannot be used. As a result, most cameras with Live View shooting have sensor-based AF systems that use contrast detection AF, which calculates focus by noting contrast differences in the image and moving the lens back and forth to achieve focus. This takes considerably longer than phase-difference detection. For speedier focus, Dual Pixel CMOS AF locks and tracks focus on the first try, without hesitation.


Each pixel on the EOS 70D camera's sensor consists of two independent photodiodes that function both as imaging points and as individual phase-difference AF sensors. When the shutter button is pressed, parallax images on each photodiode of the pixel are detected, the amount of lens drive is calculated to correct the amount of shift in the AF points, and AF is achieved nearly instantaneously. During image capture, the same two photodiodes record the image and output as a single pixel. By placing approximately 40.3 million photodiodes on the camera's sensor, two per pixel, this caliber of AF is possible on approximately 80% of the image plane, vertically and horizontally. When the image or video clip is being captured, the CMOS sensor behaves as it always has with EOS SLR cameras, unimpeded by the dual photodiodes and recording each individual pixel with virtually no loss of detail or sharpness.

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