The folks at DxOMark published a test of the Canon EOS 70D‘s auto-focus and compared it to the Sony A77‘s AF. While being interesting the comparison with the A77 was done using different lenses, the excellent EF 40mm f/2.8 STM for the Canon and the DT 16-50mm f/2.8 OSS SSM for the Sony. In the conclusion they write:
The Canon EOS 70D is an attractive proposition for both stills photographers and video users. The new Dual Pixel CMOS AF cleverly solves the problem of the redundant viewfinder based phase detection AF system when recording video and neatly avoids the patented trans-missive mirror solution adopted by Sony.
As well as retaining an optical viewfinder, the Dual Pixel CMOS AF sensor with its total of 40 million pixels used for image capture shows a small but palpable increase in lowlight performance and higher levels of sharpness than previous APS-C cameras from the firm.[…]
For video enthusiasts, this camera is one of the best choices available on the market currently and at least is a viable option to the entirely likeable and very capable Sony SLT models