Friday, July 12, 2013

Canon EOS 70D Dual Pixel Autofocus Speed Comparison

Video samples are up of the Canon EOS 70D live view autofocus in action.These are courtesy of out of Poland. The first sample is with the EF-S 18-135mm f/3.5-5.6. Unfortunately, they only show target acquisition with still subjects in the center of the scene, but the early operation looks promising.

Even with just the kit lens, AF acquisition speed appear fast and accurate.

And this sample is with the EF 100mm f/2.8 L macro

Focus speed does seem impressively fast, and certainly faster than the previous contrast detect system used in the 60D, but it is by no means the the only fast focusing live view system. Compare to the Panasonic DMC-GH3 (Via of The Digital Camera Movies:)

Unlike the Canon, which uses a novel read-out architecture to achieve phase detection focusing, the GH3 is a conventional contrast detect  system. However, it achieves this by driving the sensor at 240 fps read out, meaning that the contrast detect system is sampling the scene at a much faster rate.  However, while the GH3 has a very fast lock on speed, it's motion tracking capabilities for still photography are not as good as with the phase detection systems. Note also that the 70D video samples are of still subjects; motion tracking remains to be seen.

And finally, here's a sample of live view focusing with the Sony SLT-A55 (via

In the Sony SLT system light from the lens is split into two paths by a half-silvered pellicle mirror, one to the sensor and the other to a phase detection array. Very fast video focusing can be achieved this way, but focus tracking is confined to the area covered by the PD array.

Just a cautionary tale: It is difficult to make comparisons about which system is fastest from this video samples, as autofocus speed is also defined by the focus throw of the lens used. Some lenses are geared faster than others, but it seems that Canon's system does indeed offer a fast live view focusing system that is comparable to the other fast systems offered by Panasonic and Sony.

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