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EOS 80D Interview with Developers (Part 1): Major Improvements to AF Performance

The new EOS 80D is packed with a wide variety of new technologies. In this series of interviews, the EOS 80D developers talk passionately about the development concepts and process. Here in Part 1, we asked them about the advantages that users can enjoy with focus on major improvements made to AF-related technologies, such as the Dual Pixel CMOS AF. (Interviewer: Ryosuke Takahashi   Group photo: Takehiro Kato)

(Back row from left)
Kohei Furuya (ICP R&D Center 2)/ Koji Ikeda (ICP Development Center 2)/ Terutake Kadohara (ICP R&D Center 2)/ Takashi Ichinomiya (ICP R&D Center 2)/ Yuichiro Sugimoto (ICP Division 1)

(Front row from left)
Takashi Kishi (ICP Development Center 2)/ Masahiro Kobayashi (ICP Division 2)/ Nobuyuki Inoue (ICP Development Center 2)/ Koji Sato (ICP Development Center 1)/ Yutaka Watanabe (ICP Development Center 1)

 

Enhanced Dual Pixel CMOS AF

- What is the development concept of the EOS 80D?

Kobayashi: The concept we adopted is “professional and orthodox”. The EOS 80D is equipped with professional shooting functions comparable to the higher-end models, while conservative improvements have been made to the traditional camera features on the  EOS 70D. Canon has been striving to achieve greater “speed, comfort and quality”, which is the concept behind EOS cameras, for its middle-class DSLRs. It is important that this class of cameras address the needs of users who wish to produce shots with more professional quality. The EOS 80D has also been developed based on the same concept.

- What improvements have been made to the Dual Pixel CMOS AF?

Kadohara: First of all, operation of the Dual Pixel CMOS AF is no longer constrained by the type of lens in use. On the EOS 80D, the Dual Pixel CMOS AF is able to establish focus for all EF lenses that support autofocusing and also when an extender is in use. Not only so, the EOS 80D also supports continuous Live View shooting with Servo AF, which is a first for EOS cameras that are equipped with the Dual Pixel CMOS AF.

 

DUAL PIXEL CMOS AF

Two photodiodes that can also be employed for AF are arrayed within a single pixel. They detect the position of the subject in a waveform. The amount of misalignment in this waveform is then used to calculate the distance from the subject and move the focusing lens element quickly to the appropriate focusing position. This mechanism is fundamentally different from that of contrast AF.

- Please tell us more about the advantages of the new image sensor from the user’s perspective.

Kishi: Various efforts have been made to enhance the image quality and speed. Our users can now enjoy images with a higher resolution of approximately 24.2 megapixels. Also, it boasts a normal ISO speed range of ISO 100 to 16000 and a still shooting speed of up to about 7 fps.  The new image sensor also supports both Full HD and 60p movie shooting as well as the Dual Pixel CMOS AF.

- I believe the amount of information would become tremendously larger with an increase in the pixel count. Were any special efforts made when developing the image sensor?

Kishi: In addition to reading out data from the CMOS sensor, performance of the image processor is also another important factor. In fact, DIGIC 6 has played a vital role in achieving 50p/60p movie shooting in Full HD. We can therefore say that the combination of the image sensor and processor has made it possible to achieve high speed as well as a high pixel count.

- I believe it is technically challenging to introduce Dual Pixel CMOS AF on the image sensor while increasing the pixel count. Am I right?

Kishi: Sorry if my explanation is a little conceptual. We introduced a wide variety of technologies and efforts from reading out data from the pixels up to transmission through the circuit and processing by the image processor. We also did our best to employ the latest technologies in the miniaturisation of the image sensor.

 

Advantages of having 45 AF points

- The number of AF points has been increased to 45. What are the advantages of this in an actual shoot?

Kadohara: Compared to 19-point AF, we added AF points to the diagonally opposite corners of the angle of view. Doing so offers greater flexibility when composing a shot. A large number of AF points also makes it easier for forming a sort of “surface” made up of AF points. This prevents the focus from falling to the background instead of the intended subject when 45-point automatic selection AF is selected. At the same time, it also enhances performance in the tracking of moving objects.

- Numerically speaking, to what extent has the coverage improved with the increase from 19 AF points to 45?

Kadohara: The coverage has improved by about 120%, which is equivalent to approximately 2.2 times.

- When determining the layout of the AF points, was there any aspect you took extra effort in, or were extremely particular about?

Kadohara: The 45 AF points of the EOS 80D is derived from the 65 AF points employed on the system for the EOS 7D Mark II. When we were developing the EOS 7D Mark II, capturing the subject with a “surface” of AF points was what we worked towards achieving. The same concept applies to the development of the EOS 80D.

- Does the AF sensor of the EOS 80D share any common characteristics with that of the EOS 7D Mark II?

Ichinomiya: The body size of the EOS 80D is small compared to that of the EOS 7D Mark II, so we developed a new compact AF sensor while maintaining a high level of performance. As with the image sensor, we employed a miniaturisation process to downsize the body. Meanwhile, the increase in the low light limit to EV-3.0 can be attributed to the pixel structure, which is the same as that of the AF sensor for the EOS-1D X. These technologies reduce noise thoroughly, allowing us to achieve the low light limit of EV-3.0.

- What is the pixel structure like for the AF sensor of the EOS-1D X?

Ichinomiya: We are unable to disclose the details, but we have positioned the antenna-like part for converting light to electrons so that the noise it picks up is minimal. This technology was first developed for the EOS-1D X, and is now gradually employed on mid-range models as well. For the AF sensor of the EOS 80D, we achieved a high level of performance by developing a structure that further prevents noise from being picked up.

- Can you give some specific examples to help us visualise the brightness of EV-3.0 more easily?

Ichinomiya: Generally, the brightness is almost equivalent to that of a full moon or moonlight. While the same low light limit is also available on the EOS 6D, we have received feedback from some users saying that no flash light is needed even when capturing areas not illuminated by the spot light at a wedding ceremony. This is one of the examples that show the performance of EV-3.0.

- Just now you mentioned moonlight. With which types of subject would AF function under the moonlight?

Ichinomiya: Subjects with a stark contrast would be ideal. If we’re thinking along the lines of black-white contrast, something like what you get on a zebra or a panda, perhaps? For human subjects, AF would be able to detect our eyes, since they have a relatively strong contrast compared to other parts of the body.

- There are more AF points that are compatible with f/8. What are the advantages of this?

Kadohara: When you have a lens and an extender, you can now carry out AF with multiple points, although there are restrictions on the combination of lens and extender. AF is also possible if the composite f-number is f/8, which comes in handy when using a super telephoto lens for wild bird and sports photography. Up to 27 AF points can be used at the same time, thus making it easier to capture the subject with a “surface”.

- Which are the lenses that support AF at f/8?

Kadohara: Among the existing lineup, we have the EF100-400mm f/4.5-5.6L IS II USM and EF200-400mm f/4L IS USM Extender 1.4x. The camera makes use of the Group G focusing pattern, where the nine AF points at the centre support cross-type AF while the areas on the two sides allow for horizontal line-sensitive focusing with Single-point AF. For combinations such as the EF 70-200mm f/4L IS USM and Extender EF 2×III, cross-type AF is possible with the centre AF point using the Group H pattern.

Group G focusing pattern, which supports AF with up to 27 AF points.

A: Cross-type Focusing
B: Horizontal Line-sensitive Focusing

 

Group H focusing pattern. For the EF100-400mm f/4.5-5.6L IS II USM + Extender EF1.4x III or EF200-400mm f/4L IS USM Extender 1.4x + Extender EF2x III combination, highly-precise cross-type focusing is possible with the centre AF point.

A: Cross-type Focusing

 

Evolution of the AI Servo AF II

- What types of scene are made easier with the addition of Large Zone AF?

Kadohara: The AF area is divided into three zones, which is useful when you are taking a close-up shot of the subject as well as when you want to take a trial shot by determining the rough position of the subject. The area it covers is wider than that of Zone AF, thus making it suitable too for tracking moving objects.

- What is the best way to differentiate the use between AI Servo AF II and 45-point automatic selection AF?

Kadohara: Large Zone AF is recommended when there is a fair amount of movement in the subject and when you want to maintain the focus within this area so that the composition will not be affected. It comes in handy when the subject is moving up and down within the zone.

Large Zone AF on the EOS 80D

 

- What advancements have been made on the new AI Servo AF II?

Kadohara: It now comes with a colour tracking function. AI Servo AF II utilises the 45-point all cross-type AF, which significantly enhances the tracking performance of moving objects over a wide area. Conventional Servo AF basically selects an AF point and calculates the point to focus based on the AF information. However, AI Servo AF II on the EOS 80D also makes use of colour information for AF point selection in addition to this, which further helps to boost the precision.

- What kind of function is AF point auto switching?

Kadohara: AF point auto switching is intended for customising the AF point characteristics when there is vigorous movement in the subject. It mainly functions during automatic AF point selection, and allows you to set the switching sensitivity of the AF point for moving subjects. [0] is the standard setting for gradual AF point switching, while setting it to [+1] or [+2] increases the switching sensitivity. However, increasing the switching sensitivity may cause the camera to switch to an AF point that is different from that intended in some cases.

 

- How does the Initial AF point for AI Servo AF function during 45-point automatic selection AF?

Kadohara: “Initial AF point for AI Servo AF” is a feature for determining where to start AI Servo AF. You can either let the camera determine the point automatically or make a selection manually. Furthermore, there are two ways of manual selection. One way is to make use of a specific AF point selected for Single-point AF, and the other is to use the AF point selected for 45-point automatic selection AF before AI Servo AF starts.

- How is colour tracking associated with this feature?

Kadohara: Colour tracking is enabled by default. If Initial AF point is set to Auto, the camera first searches for colours equivalent to the skin tone and selects an AF point within the zone to establish focus if such a colour is detected. Once tracking starts, the camera selects an AF point and continues focusing based on information including the colour. Priority is given to establish focus on colours equivalent to the skin tone even when there are other objects between the subject and the camera.

- How does it behave for colours other than skin tone?

Kadohara: If colours equivalent to the skin tone are not detected, the camera selects an AF point and establishes focus according to the nearest subject, and starts tracking the subject once focus is achieved. While colour information is also made use of to select an AF point for the tracking operation in this case, it is not limited to a specific colour.

- How should I use this feature if I want to track the focus of a subject that is positioned slightly far away from the camera, such as a red car or a green train?

Kadohara: To do so, set Initial AF point for AI Servo AF to Manual AF point for the camera to establish focus on the target subject. By doing so, you will also be able to make use of colour information for tracking the subject. However, colour tracking may not be accurate if the subject is located too far away.

- What is the estimated area needed for colour tracking with respect to the viewfinder area?

Kadohara: As a rough guide, the area should be slightly larger than the AF point. Colour tracking will be more accurate if the size of the subject is larger.

 

 

Ryosuke Takahashi

Born in Aichi in 1960, Takahashi started his freelance career in 1987 after working with an advertising photo studio and a publishing house. Photographing for major magazines, he has travelled to many parts of the world from his bases in Japan and China. Takahashi is a member of the Japan Professional Photographers Society (JPS).

 

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

 

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