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EOS 5D Mark IV Interview with Developers (Part 4): The Live View and Viewfinder AF Systems

The tremendously improved AF system on the EOS 5D Mark IV and its benefits to Live View shooting are the main topic of this final instalment of our interview with the developers of the EOS 5D Mark IV. (Interviewer: Ryosuke Takahashi, Group photo: Takehiro Kato)


(Back row, from left)
Kazuki Haraguchi, Megumi Inazumi, Keisuke Kudo, Yasuyuki Watazawa, Takashi Kon, Kiyoshi Tachibana, Yutaka Kojima, Hiroaki Nashizawa


Significant changes to the viewfinder and Live View AF systems

- Is the AF sensor on the EOS 5D Mark IV the same as that used on the EOS-1D X Mark II?

Kojima: Yes, we used the same AF sensor model for both cameras. Other than the parts for securing it to the camera body, the rest of the parts employed are exactly the same as those used on the EOS-1D X Mark II.

- The AF system is significantly different compared to that of the EOS 5D Mark III. Could you tell us how the shooting system has changed?

Kudo: First and foremost, we have made changes to the viewfinder system. By increasing the maximum number of AF points to 61, all of which support a maximum aperture of f/8, not only is the camera capable of capturing even better photos of subjects, the range of photographic possibilities has also widened when shooting with a lens extender. Also, the low light limit has been further lowered to better handle shooting at dimly-lit locations.
The EOS 5D Mark IV now supports the EOS iTR AF system, which detects the shape and colour of the first subject that the camera sets focus on when the subject tracking AF function is used for viewfinder shooting. This enables the camera to perform tracking while switching the AF points. Not only so, advancements have also been made in the tracking performance such as with the updated tracking algorithm.
As for the Live View shooting experience, adopting Dual Pixel CMOS AF has brought about dramatic changes to the Live View shooting style. In particular, the camera is now able to handle a much wider variety of scenes with the higher AF speed.

- Dual Pixel CMOS AF is a technology that was first adopted on the EOS 70D but not on the two EOS 5DS models. What was the reason for introducing it on the EOS 5D Mark IV?

Tachibana: Actually, we had wanted to introduce it on the EOS 5DS series too. However, that would have been rather technically challenging because of the 50.6-megapixel resolution, which is why we eventually did not include it. One of the reasons we adopted it on the EOS 5D Mark IV is because we succeeded in overcoming those technical difficulties. [Editor's note: This is further elaborated in Part 2 of the EOS 5D Mark IV Interview with Developers.]

For more about how the Dual Pixel CMOS AF differs from conventional AF, read:
EOS 70D Interview with Developers Part 2: Unveiling the Dual Pixel CMOS AF


- I believe the AF system of the EOS 5D Mark IV belongs to the same generation as that of the EOS-1D X Mark II. Is there any area where the EOS 5D Mark IV surpasses the EOS-1D X Mark II in performance?

Kudo: The defining difference between the two models lies in Live View AF rather than viewfinder AF. Both cameras are equipped with Dual Pixel CMOS AF, but the EOS 5D Mark IV allows users to select from the three types of AF: Face detection + Tracking AF, FlexiZone – Multi AF (maximum 63 AF points) and FlexiZone – Single AF. The EOS-1D X Mark II offers only Face detection + Tracking AF and FlexiZone – Single AF.
Also, Servo AF can now be used too for still photography, which helps to enhance the capability of tracking moving objects. Besides, the same Servo AF now comes with an extremely wide array of functions, including a Focus priority mode and a Shooting speed priority mode.
The low light AF performance during Live View shooting supports lighting as dim as EV-4 – the lowest in the entire EOS series and more powerful than the low light limit of EV-3 on the EOS-1D X Mark II when photographing in dimly-lit scenes.

- The low light limit of EV-4 is even better than the low light AF performance of the viewfinder, am I right to say that?

Tachibana: Yes, you are right. The viewfinder image would appear dark too in a dimly-lit scene, and there are occasions where we are unable to identify whether the image is in focus. With the better low light performance of the Dual Pixel CMOS AF on the EOS 5D Mark IV during Live View shooting, it is now easier to establish focus. Also, the Live View image is displayed on the LCD monitor, which allows you to adjust the display for the image to appear brighter than what you actually see. This makes it easier to identify the subject and comes in extremely handy when you are shooting at a very dark location.


Advantages of Live View AF

- In what aspects do the Live View AF surpass the viewfinder AF on the EOS 5D Mark IV?

Kudo: One of the advantages of Live View AF is that it covers 80% x 80% of the screen area during AF shooting. Although the performance of the viewfinder is also excellent with 61 AF points, the area that can be covered by AF is limited. Meanwhile, the biggest advantage of Live View AF is that it offers a wide area for AF, and you can set focus freely on any point within this area without being constrained by the position of the AF points. Yet another advantage of the EOS 5D Mark IV is the use of a touch-screen for features such as Touch Focus and Touch Shutter, which allows for intuitive operation during the shoot.

- Many users have reservations about using Live View AF because of the large AF frame. What are the measures taken on the EOS 5D Mark IV to address this concern?

Kudo: We are aware of the calls for a smaller AF frame. But we have maintained it at the same size after considering its balance with the AF performance. The EOS 5D Mark IV now supports AF shooting while the image is enlarged, and it is also easier to move the AF frame via touch-screen operation. The LCD monitor also boasts a clear display and high definition, so I believe users who have not tried the Live View function before would also find it useful.


How to establish focus during Live View shooting

(1) Tap the position you want to set focus on to select it

Select the point you want to set focus on directly on the screen.


(2) Press the Index/Magnify/Reduce button


Enlarging the image allows for more precise focusing.


(3) Turn the focusing ring to fine-tune the focus

In addition to focusing using AF, you can also choose to focus manually with MF.


- In terms of structure, including also the viewfinder optics, what improvements have been made compared to the EOS 5D Mark III?

Kojima: The main specifications such as coverage and eyepoint remain the same as those on the EOS 5D Mark III, but we have made substantial changes to the details.

- Were enhancements made to the optics in the eyepiece too?

Kojima: Yes. We have introduced measures to thoroughly reduce aberrations that tend to occur in the viewfinder optics, such as chromatic aberration of magnification. Besides adopting new materials for the optical system, we have also enhanced the apparent resolution of the viewfinder by further improving the accuracy of each and every component. Although the viewfinder on the EOS 5D Mark III is almost close to perfection, you can see the viewfinder on the EOS 5D Mark IV as a more refined version. I believe users will be able to feel the improvement in the viewfinder clarity compared to the EOS 5D Mark III, although this difference might vary in degree across individuals.

To learn more about other improvements to the body of the EOS 5D Mark IV, read:
EOS 5D Mark IV Interview with Developers (Part 1): Development Concept & Improvements to the Body

- The battery grip has also been updated. What improvements have been made?

Kojima: For the new Battery Grip BG-E20, we tried our best to arrange the buttons around the shutter release so as to offer the same feel regardless of whether users are operating them with the camera held vertically or horizontally. Also, to cater to movie shooting, we included a hole for the video pin, which prevents displacement of the camera during panning when it is mounted on the tripod platform, beside the tripod mounting hole at the bottom surface. This is in response to requests asking for compatibility with video pins now that we have a greater number of users who are shooting movies with DSLR cameras.



- An AF area selection button has been newly added to the rear of the battery grip body. What is the purpose of adding this button?

Kojima: Viewfinder AF on the EOS 5D Mark IV now supports 61 AF points that cover a wider area. The AF area selection button is one of the most user-friendly features on the EOS 5D Mark IV body, and we decided to incorporate this into the battery grip to enhance the operability further. We chose a button design instead of a lever because we wanted the design to be consistent with that of all other buttons and controls.


The same controls as those on the EOS 5D Mark IV can be found at the rear of the Battery Grip BG-E20, which help to enhance users’ experience when operating the camera in both the vertical and horizontal orientations.


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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


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