And when you factor in DSLR lenses and Live View, it’s near impossible for a single operator to keep tack-sharp focus. DSLR lenses are meant for shooting stills, and the AF (autofocus) function is designed to perform superquick lens adjustments. Because of this, the focus throw on an AF lens barrel is very short, so when shooting continuous video with subjects and objects constantly changing position throughout the frame, it makes it extremely hard to keep things in focus manually. Autofocus? Due to the long focus lag and the noise the lens motor creates, it’s really not an option.For single-operator DSLR movie shooters, Canon’s new EOS 70D looks to change that.
Canon is marketing the 70D as the first DSLR that you can shoot like a camcorder. On the surface, in terms of specs, the 70D is a decent step up from the 60D, but not a huge one. The camera contains a 20.2-megapixel CMOS sensor, DIGIC 5+ Image Processor and an ISO range of 100-12,800 (expandable to 25,600). For stills, you can shoot 7 fps, and it has an impressive 19-point all cross-type AF system.
For video formats, the 70D can capture 1080p full HD video up to 30 fps in either ALL-I or IPB codecs, which is similar to that of the EOS 1D X, 5D Mark III and 6D. Unlike the 5D Mark III, which uses both CF and SD/SDHC/SDXC cards, the 70D has a single SD/SDHC/SDXC card slot that supports the Ultra High Speed (UHS-1) cards.
A cool feature is a new built-in Wireless Transmitter that gives you connectivity options to share images via Wi-Fi. There’s a free EOS Remote app from the Apple App store or Google Play store that allows you to transfer photos and videos from the camera to your device wirelessly. And you can control aperture, shutter speed and ISO from your mobile device if your camera is mounted out of reach.
DUAL-PIXEL CMOS AF
Up until now, with the exception of Sony A99’s continuous AF mode, autofocus for DSLR video has been subpar. But before I get into the 70D’s new AF system, I know what you’re thinking. Professional filmmakers simply don’t use autofocus to keep their shots in focus. This is true. Manual selective focus by a talented focus puller can sometimes enhance the story by finessing speed, timing and subjectively selecting particular objects in the frame. Autofocus will most often eliminate that.
Canon’s Dual-Pixel CMOS AF uses phase-detection technology. In greater detail, each pixel in the 70D’s sensor is composed of two photodiodes. Phase differences between each photodiode are continuously compared on a per-pixel basis to generate constantly updated, real-time autofocusing data. At the same time, each pixel produces image data in the same way as a conventional sensor. Canon engineers had to develop an algorithm that would allow the camera to autofocus successfully with a wide variety of subject matter, including challenging high-contrast situations such as sunshine filtering through foliage or reflecting off car hoods. They performed countless hours of tests to keep improving the algorithm. What makes this technology unique is that the 70D’s image performance is maintained with no loss in quality.