It's become increasingly rare for any manufacturer to show us technology that's genuinely innovative and unique, but that's exactly what Canon has done with the EOS 70D and its 'Dual Pixel CMOS AF' sensor. It's fair to say that on-sensor phase detection AF has so far shown lots of promise without necessarily being truly transformative to the shooting experience of most the cameras that use it, with Nikon's 1 System cameras being the most obvious exception. But while these offer exceptional focusing performance in good light, especially with regards to tracking moving subjects, the AF system can struggle the moment you try shooting indoors with a zoom lens.
Canon's approach of splitting every single pixel on the sensor into two separately readable photosites promises, in theory at least, to overcome the biggest problems that have afflicted on-chip phase detection systems to date. We're certainly excited by what it claims to offer in principle - the ability to work across a large area of the frame, at apertures down to F11, and in low light is a pretty compelling combination. Throw in such goodies as face detection and tracking, and focus point selection by touch, and on paper the EOS 70D looks like it could offer the best live view autofocus of any camera on the market, bar none. Our early experience, gleaned with a few days spent with a beta sample of the camera, is very encouraging and we'll be publishing more in the coming days.