Canon 70D Review – A Closer Look at the Canon 70D’s Autofocus Technology
Like its predecessors the Canon 70D has a great touch screen interface. It allows you to tap through menus and even during playback – it’s a real bonus over the more clunky controls of rival DSLRs.
Canon has also sensibly widened the optical viewfinder coverage and boosted continuous shooting to 7fps. This is a solid improvement over the 60D and brings it closer to the capabilities of its flagship models.
1. Dual Pixel CMOS AF
The Canon 70D is an excellent mid-range DSLR that offers a lot of features at a reasonable price. It uses Dual Pixel CMOS AF, a new technology that offers high-speed, accurate autofocus for stills and video.
Technically, Dual Pixel CMOS AF is image plane phase detection, but it does so in a very different way. In fact, every pixel on the CMOS sensor can perform both phase detection and imaging.
This enables the camera to focus much faster and more accurately – particularly in Live View. This is a big benefit for filmmakers who use a ‘run and gun’ approach. It also works in a wider range of lighting conditions than conventional AF systems.
2. Dual Pixel CMOS AF for Movies
Whether you’re a pro videographer or a one-person shooter, focus is critical. That’s why Canon’s Dual Pixel CMOS AF is such an amazing innovation.
First introduced in 2013, this technology combines image-sensor phase-difference autofocus with Live View shooting. It provides faster focusing performance and outstanding subject tracking, especially when a camera is in Movie mode.
It works by splitting the photodiode for each pixel into two halves, and reading out data corresponding to top-arriving and bottom-arriving light rays. This enables the system to determine a subject’s direction of movement in real time, and command the lens to move accordingly. It’s also very smooth and responsive, allowing you to change focus effortlessly as a subject moves around your frame.
3. Dual Pixel CMOS AF for Portraits
Dual Pixel CMOS AF (also known as DPAF) is Canon’s unique sensor-based system that dramatically improves Live View and video autofocus speed. It can also be used to create professional-looking pull-focus effects.
While traditional contrast-detect systems seek out focus by moving the lens back and forth until they find it, Dual Pixel AF uses every pixel of the image sensor to detect a subject’s position. This enables it to achieve smooth, consistent focusing at all times – even when tracking a fast moving object.
This system also eliminates face detection limitations by allowing you to place a custom AF point over a detected face and have it follow it.
4. Dual Pixel CMOS AF for Landscapes
Since 2013, Dual Pixel CMOS AF has been an incredibly popular feature in Canon cameras, from the $10,000 EOS C300 cinema camera to the entry-level EOS Rebel T7i. It’s easy to see why—it allows for faster and more accurate autofocus than ever before, without the need for a dedicated AF sensor.
This works by splitting each image pixel into two sub-pixels that capture light from different angles, and then combining them for readout. This improves AF speed and accuracy by reducing ‘hunting’, when the camera moves back and forth in search of a subject.
It also enables Face detection, which detects a person and automatically creates a custom AF area around it. This can be very useful for videomakers, especially those with small crews.
5. Dual Pixel CMOS AF for Sports
Rudy Winston has been with Canon USA’s Pro Products team for over 20 years and is responsible for training staff on new EOS cameras, creating product presentations for customers and dealers, and various writing projects. He contributes regularly to the online articles and resources on Canon’s Digital Learning Center.
Launched in the EOS 70D in 2013, Dual Pixel CMOS AF is a phase-detection autofocus technology conducted directly on the image sensor plane. This makes it easy to achieve smooth, high-performance tracking for movies or Live View shooting with stills. It also helps create professional-looking pull-focus effects in movies, while delivering fast and precise focus in Movie Servo AF mode.
6. Dual Pixel CMOS AF for Macro
The 70D’s Dual Pixel CMOS AF also works great for macro shots of tiny subjects. Even with the camera set on a tripod and using Live View, the ability to easily focus on and track the subject’s eyes makes it easier than ever to get amazing close-up images.
Increasing the number of AF points or the size of the AF area would have required Canon to reduce the image sensor’s imaging pixels. Instead, the AF system uses information from every pixel before and during image recording to help determine sharpness, making it faster and more accurate than traditional contrast-detect AF. And it works with nearly all Canon EF and EF-S lenses.