While the movie-shooting feature of DSLR cameras is highly rated for its excellent image quality, one of the imperfections that are commonly pointed out is their AF performance. However, the introduction of the Dual Pixel CMOS AF on the EOS 70D has brought about revolutionary changes to movie AF. In the second article of this series that explores the movie AF feature on the EOS 70D, I will test how well focus can be established through touchscreen operated focusing and make use of ”fall-down” crane shots to assess the face detection feature. (Edited by: Video Salon, Report by: Kazuhiko Saika)
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AF via touchscreen operation allows you to shoot professional-quality movies
When using the "FlexiZone - Single" AF mode on the EOS 70D, you can use the touchscreen to establish focus on the selected point while shooting movies using the Live View function. Doing so allows the focus to shift smoothly during the shoot. Although you can also shift the focus using manual focusing while recording is in progress, this involves turning the lens with a hand to adjust the focus, causing shake that thus results in unstable images. Shifting the focus via the touch focus operation on the EOS 70D helps to minimise the possibility of camera shake, allowing users to achieve a professional level of quality in "rack focusing".
1. I started recording with the focus set on the far end of the image.
2. When I tap the onscreen image of the portrait subject on the right, the camera establishes focus on her.
3. I tapped the portrait subject on the left to shift the focus to her.
4. Tapping the subject on the right again moves the focus back to her.
AF shooting is possible even when you are unable to reach the focusing ring in a crane shot
This movie was shot using the EOS 70D with the AF mode set to [Face + Tracking AF]. I wanted to check the extent to which the camera is able to capture the images when autofocusing work is left completely to it. I adjusted the focus using the touchscreen operation only when the subject was too far away from the camera and the face was too small. Otherwise, I left it to the camera's AF to set the focus. Face detection AF and automatic tracking offer significant advantages in situations where focusing operation is difficult, such as in shoots that make use of a crane, or those that involve extremely high or low angles.
Focusing work that does not rely on face detection is also necessary for "fall-down" crane shots
In [Part 1] EOS 70D - Revolutionary AF Performance, I wrote about the advantages of the EOS 70D's movie AF performance. In the [Face + Tracking AF] setting, the EOS 70D establishes focus using the optimal (or rather, the best possible) AF point by switching to [FlexiZone - Multi] temporarily when it loses track of the subject's face. However, depending on the situation, some issues may remain unresolved. When I tested the camera in scene where a crane was used to pan the camera up and down the human subject, as illustrated below, the EOS 70D switched to [FlexiZone - Multi] when it failed to detect the subject's face. This caused the camera to shift the focus to the centre of the image. To prevent this from happening, you can make use of [FlexiZone - Single] to establish focus. It would be good to have a customisable function that temporarily stops the focusing mechanism until the camera detects the subject's face again when the face detection feature loses track of the face.
1. I started taking a fall-down crane shot in the [Face + Tracking AF] setting.
2. Focus is highly precise when the camera is able to detect the subject's face.
3. I lowered the crane further so that the face of the subject is no longer within the frame. The face detection feature of the camera lost track of the subject's face.
4. The camera switched to [FlexiZone - Multi] when it failed to detect the face, and established focus on what it considers to be the subject.
* Unless otherwise stated, the EOS 70D Kit II (EF-S18-135mm f/3.5-5.6 IS STM) was used for this test.
Currently a professor with the Faculty of Media and Information Resource at Surugadai University, Mr. Saika was formerly a planning producer at an advertising company and a certified trainer for a high-end editing system. His recent artistic activities centre on videography with DSLR cameras, and he is currently experimenting with 4K videos.
Video Salon started publication in 1980, and is Japan's only niche magazine on videographic equipment. Catering to readers who range from serious amateurs to professionals, it enjoys an established reputation not only for the information it provides on video cameras and editing software, but also on its drive-run reviews on videography with the latest DSLR cameras and its expert tips and tutorials.
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