EOS 6D Mark II: What You Should Know About Dual Pixel CMOS AF and Live View AF
Two major key features of the EOS 6D Mark II are the Vari-angle touch screen LCD monitor and Dual Pixel CMOS AF that enables high-speed autofocus (AF). With 2 AF operations and 3 AF methods available, you can choose the configuration that best suits your scene, and through that, capture images that were previously impossible to capture. This article examines the Dual Pixel CMOS AF and the AF system in Live View, so you can understand and make the most of these features during your shoot. (Photos and text by: Ryosuke Takahashi)
What is Dual Pixel CMOS AF?
Dual Pixel CMOS AF, which is one of the key features on the EOS 6D Mark II, is, in a broad sense, a feature that falls under technology known as phase detection AF. However, unlike the conventional AF method whereby dedicated AF pixels are placed between imaging pixels, in Dual Pixel CMOS AF, all of the pixels on the image sensor are used for both autofocus (AF) and imaging, thus making autofocus possible across 80% of the image display area, both horizontally and vertically. It goes without saying that this offers a lot of flexibility in the selection of the focal position. Not only so, unlike with Contrast AF, the camera does not have to hunt for the focal position, which dramatically reduces the time required for focus to be established. Furthermore, with Dual Pixel CMOS AF, the camera is able to detect shifts in movement and ensure accurate AF on the subject, which makes full-fledged Servo AF continuous shooting possible.
Each pixel on the CMOS sensor in Dual Pixel CMOS AF consists of two photodiodes, which independently send information on the distance of the subject for the camera to achieve accurate focusing.
Field test: Verifying the response time of different AF methods
For the images below, I used the three AF methods to capture a train that was coming toward me. Comparing them, you can observe that the focusing capability of the Dual Pixel CMOS AF is fast enough to rival that of Viewfinder AF, with almost no difference between the two methods. In contrast, the Contrast AF example, which was shot with the EOS 6D, confirms that the camera takes some time to look for the focal position using this method.
Green line: The position where the shutter was released
Red line: The position where the shutter started releasing
Dual Pixel CMOS AF
Field test: Verifying AF accuracy during macro photography
Here I photographed and compared photos of a teddy bear. While Viewfinder AF focused on a point in front of the teddy bear's eyes, Dual Pixel CMOS AF was able to focus accurately on the eyes of the teddy bear. This is because the pixels used for autofocus are also used for measuring distance, thus achieving accurate focus. Another advantage of Dual Pixel CMOS AF is that it enables you to enlarge the image on screen to specify the focal point.
(Left) Shot with Viewfinder AF: Focus was established on the part of the eye that was nearer the camera, which leaves the area to the left slightly out of focus.
(Right) Shot with Dual Pixel CMOS AF: The entire eye is sharply in focus.
How to achieve focus swiftly with Touch AF
The EOS 6D Mark II is equipped with a Vari-angle LCD monitor, which makes shooting in Live View possible. You can use Touch AF to achieve focus quickly, even as you are looking at the Live View screen.
1. Switch to Live View
Set the lever indicator to the Live View position, and press the button to launch Live View.
2. Select the exposure mode
While holding down the Mode Dial lock release button, turn the dial to select the shooting mode.
3. Configure settings quickly with Quick Control
Press the Quick Control button to select your desired AF method. Here I selected Smooth Zone AF.
4. Focus using Touch AF
Touch the LCD monitor on the rear side of the camera to focus. You can also move the position by sliding your finger across the screen.
Understanding the AF system in Live View
The AF system in Live View consists of two AF operations and three AF methods. AF operation refers to one of 2 operations: One-Shot AF and Servo AF. AF method, on the other hand, refers to the feature that allows you to select the number and movement of AF points to be used.
When shooting with Live View on the EOS 6D Mark II, AF operation and method are combined to track the movement of the subject. It is therefore very important to understand the characteristics of how each combination operates.
Do be well aware though that the newly added Smooth Zone AF has different AF point behaviour in One-Shot AF and Servo AF. Moreover, with Face+Tracking AF, you can now touch the screen to enable or disable face detection, thereby changing the characteristics completely. By understanding these characteristics, you can make the most of the AF feature according to your subject.
One-Shot AF + Face+Tracking AF
When using face detection, the AF point is displayed automatically and shifts laterally according to the movement of the face.
Servo AF + Face+Tracking AF
The face is detected automatically and is tracked laterally. At the same time, the camera maintains focus by tracking the focusing distance of the subject.
One-Shot AF + Smooth Zone AF
The subject is captured within any specified zone. Once focusing has been confirmed, the number of active AF points does not change.
Servo AF + Smooth Zone AF
The subject is tracked laterally and longitudinally while the number of active AF points changes within the selected zone.
One-Shot AF + FlexiZone - Single AF
The selected AF point is used for focusing. There is no AF tracking.
Servo AF + FlexiZone - Single AF
The focus is tracked longitudinally in any selected AF point. There is no lateral tracking of the AF point.
Also see the following articles about the EOS 6D Mark II:
EOS 6D Mark II First Impressions Review: Landscape Photography
What’s New on the EOS 6D Mark II: 13 Key Features (Part 1)
What’s New on the EOS 6D Mark II: 13 Key Features (Part 2)
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Digital Camera Magazine
A monthly magazine that believes that enjoyment of photography will increase the more one learns about camera functions. It delivers news on the latest cameras and features and regularly introduces various photography techniques.
Published by Impress Corporation
Born in Aichi in 1960, Takahashi started his freelance career in 1987 after working with an advertising photo studio and a publishing house. Besides photographing for advertisements and magazines in and out of Japan, he has also been a reviewer for “Digital Camera Magazine” since the launch of the publication as well as published a number of works. In his product and lens reviews, Takahashi particularly advocates photography techniques that bring out the lens performance through his unique point of view and tests. Takahashi is a member of the Japan Professional Photographers Society (JPS).