After a long renewal process of about four years, the EOS 5D Mark III makes its appearance with further breakthroughs. In addition to enhancements made to the basic performance, the expressive power of the EOS 5D Mark III has also improved dramatically. Many must be curious how this new model came about. The following is a report of my interviews with the key developers on their passion toward the camera. Here in [Part 1], we will go into the story of EOS 5D Mark III's high image quality and the "super fluid style" body design. (Based on the interview held in May 2012) (Interviewer: Ryosuke Takahashi/ Photos by: Takehiro Kato)

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(Above, from left)
Noriaki Tsunai, Photo Products Group/ Makoto Kameyama, Camera Development Center/ Kentaro Midorikawa, Camera Development Center/ Shingo Nakano, Camera Development Center
(Bottom, from left)
Mie Ishii, Camera Development Center/ Masami Sugimori, Camera Development Center/ Keita Sato, Design Center/ Hiromichi Sakamoto, Camera Development Center

Standard ISO 25600 realized for the true meaning of "high image quality"

― Can you start by telling us about the overall concept of the EOS 5D Mark III?

Tsunai First of all, we have developed the EOS 5D Mark III as the successor model to the EOS 5D Mark II. In addition to making further enhancements to the high level of overall image quality that the 5D series is well-reputed for, we have also aimed to produce a camera that boasts the top level of performance in its class. Of course, emphasis was also placed on the physical appearance and quality feel to bring to our users the joy of owning the camera.

― Among the voices from the EOS 5D Mark II users, which part of the camera needed improvement the most?

Tsunai The image quality was generally satisfactory for both the EOS 5D and EOS 5D Mark II, but we have received a lot of voices on the AF performance and response. Among those on the response are requests to improve the continuous shooting performance and to shorten the release time lag. There were also other opinions on the viewfinder and moiré during movie shooting.

― Was feedback on the viewfinder related to the viewfinder coverage?

Tsunai Yes. Many of our users have a very strong passion toward the way of photographic expression they produce, so we believed it was particularly important to achieve a viewfinder coverage that is as close to 100% as possible.

― Can you tell us the reason why this pixel count was chosen for the EOS 5D Mark III?

Tsunai At the present moment, our definition of "high image quality" is not just limited to a high pixel count. Besides shooting at a bright location, there are likely to be many occasions where shots have to be taken under low-light conditions, such as at night or before dawn. So, we arrived at a conclusion that what "high image quality" truly means is a quality that is satisfactory in all aspects, including the time and place of shooting. We eventually managed to find the optimal balance by raising the ISO speed that can be put to frequent use by two stops on the EOS 5D Mark III, while settling on a resolution of approx. 22.3 megapixels.

― I see. So you did not set a target pixel count that you wanted to achieve at the beginning.

Tsunai We aimed to achieve advancement in the overall image quality with priority placed on raising the ISO speed that can be put to use frequently.

Sugimori As many of you already know, we are almost reaching the limit to which we can increase the pixel count with respect to the resolving power of the lens. We are also aware of this issue, which is why we decided that simply raising the pixel count might not necessarily be the best decision at the present point. Although we have not arrived at a conclusion on this, we have, as part of our effort to boost the image quality, introduced the "Digital Lens Optimizer" feature on the Digital Photo Professional software. The reason for doing so is because we believe that in addition to pixel count, it is also necessary to improve the overall image quality from other approaches.

― Thank you for the thorough explanation. Next, can you please tell me more about the concept and features of the design for the EOS 5D Mark III?

Sato During the development of the EOS 7D, we have established a "super fluid style" as the design concept for the entire EOS series. This is a style that realizes both an ergonomic shape that fits the hand well, as well as an aesthetically beautiful "curved surface." The new EOS 5D Mark III adheres fundamentally to this concept, while at the same time takes on a moderately tough appearance that is characteristic of the "5D" family.

― I can tell that much effort has been put into the details too, such as the buttons and grip.

Sato Yes, we have paid meticulous attention up to the minute details since we expect the camera to be used by professional photographers too, so minute that you might not even notice them (laughs). Besides the angle of each button and the feel when they are pressed, we have also made other thorough efforts to improve the operability of the controls, such as adhering a rubber material to the side of the Mode Dial. Similarly, the card slot covers are also adhered with rubber to provide a better fit to the hands.

― Which part were you most particular about when designing the EOS 5D Mark III?

Sato Actually, it was the opposite. We tried to avoid an overly elaborate appearance. Our intention is not to project a gorgeous impression, but one with a chic expression that stresses its role as a "tool." The only part with an added touch is the pentaprism. In contrast to the curved surface of the body, the pentaprism, which is equivalent to the head of the camera, was designed to look slightly rigid to exude a dignified charm. Countless trials were undertaken to determine the position of the lines and how they blend in with the body, as well as the bend angle of the planes. Also, a high level of technicality was involved to make the coated covers blend in naturally with the body, and this was made possible thanks to the support from the factory.

First gapless design in the "5" family

― About the image sensor, can you elaborate on the technical aspects that made it possible to increase the ISO speed for frequent use, while realizing both low noise and a wide dynamic range at the same time?

Ishii A part of it can be attributed to our persistent efforts, but it was also because of the further advancements that were made in the miniaturization process in response to the smaller pixel pitch as a result of the higher pixel count. The miniaturization process enables us to secure a wider photodiode area. In other words, the new design adopts a wider area for capturing light.

― The pixel pitch of the EOS 5D Mark III is about 6.25 μm. Is it correct to say that the improvements you mentioned have helped to offset the reduction in the pixel pitch?

Ishii Yes, you can think of it that way. With regard to the enhanced characteristics of high ISO sensitivity, in particular, noise tends to become more evident due to amplification of a small amount of light; even readout from the image sensor may constitute a source of noise. Since it is not advisable to amplify the data when noise is already present, we have been making improvements since the EOS 5D Mark II generation to perform amplification as close to the photodiodes as possible. This technology has also been applied to the EOS 5D Mark III.

― Were adaptations made to the shape or array of the micro lenses for the full-frame sensor?

Ishii On the EOS 5D Mark II, we have tried to reduce the gap between the micro lenses as much as possible, but with the EOS 5D Mark III, we have realized a gapless design, which is a first for the 5D series.

― It would be difficult to gather light efficiently at the edges of a full-frame sensor. Did you make any improvements such as by adjusting the angle or shape of the micro lenses?

Ishii I would say the emphasis was on the "phase" rather than the shape. We tried to improve the relative position of the micro lenses and photodiodes. In other words, since light falls on the peripheral areas of the image sensor from an angle, we shifted the position of the micro lenses sideways for light to enter the photodiodes more easily.

― I see. The next question is on the image processor. How is DIGIC 5+ different from the DIGIC 5 processor?

Sugimori The "+" that is added to DIGIC 5 symbolizes a configuration with a higher processing speed. To put it more specifically, DIGIC 5+ allows for high-speed image processing by connecting a high-speed memory to it.

― I believe a large amount of heat would be generated from the high-speed process. Are measures introduced to address this issue?

Nakano We can't possibly build a fan into the camera in the same way as what we do for a PC (laughs). Our basic approach is to ensure that the heat is dissipated in different directions. If the heat gathers at one spot, it will cause "burn injuries," or so to speak, to the other components, and the performance may deteriorate as a result. We took this point into consideration when determining where the image processor should be positioned.

― It seems to me that with the EOS 5D Mark III, apparent resolution is not lost even when you take shots at a high ISO speed. Were there any new attempts that made this possible?

Sugimori Yes. I cannot give you the details, but we have introduced a new noise-reduction technique. While it is a very effective technique, applying it excessively will result in loss of details. We had a hard time trying to adjust it to a level that balances well with the apparent resolution.

― Is the same system introduced on the EOS-1D X?

Sugimori Yes. Both models are developed at almost the same time, and they are equipped with systems that employ the same algorithm. The high ISO sensitivity on the EOS-1D X has also been enhanced using the same system.

― You have introduced 61 AF sensors within a limited space. Can you give us a better idea of the technical background that made this possible?

Nakano I can't tell you the specifics of the manufacturing know-how, but the key point lies in the performance of the AF optical system and the layout of the mechanical components. Although adopting the f/4 cross-type for all AF points helps to boost the performance, doing so increases the size of the unit, making the camera bulkier. Therefore, by combining the use of f/5.6 sensors, we were able to keep the size compact while still maintaining the focusing accuracy.

― A zigzag pattern is adopted for all the AF points. So, am I right to say that there is a need to process an immense amount of data?

Midorikawa Yes, you are right. The AF system comes with a dedicated microcomputer where all data processing work is done. The concept of the system is basically the same as that for the EOS-1D X.

― The lowlight sensitivity of the AF sensor has been expanded to -2 EV on the EOS 5D Mark III. What technologies were used to realize this?

Sakamoto We have made improvements to the pixel structure of the AF sensor. The main purpose for doing so is to cut noise, since reducing noise helps to boost the sensitivity. It is the combination of these technologies that made it possible to expand the lowlight sensitivity of the AF sensor.

― Three types of AF sensors have been employed: f/2.8, f/4, and f/5.6. How does each of these work during focusing?

Midorikawa It all starts with determining which sensor has the most reliable output. Upon taking in data output from each of the sensors, the data is sorted by a secret algorithm. This is then added with information from the zigzag-patterned sensors to determine the final point to focus.

― How has the performance of the AI Servo AF feature been enhanced compared to the algorithm of other existing models?

Midorikawa The EOS 5D Mark III adjusts all the parameters for AI Servo AF internally. Since it is impossible to employ the same algorithm for both an auto race and a figure skating performance, we have developed separate algorithms by studying their individual characteristics. The crucial difference that sets it apart from the past models is that it can now be customized.

― The menu screen of the "AF Configuration Tool" looks the same as that on the EOS-1D X. Are the functions available identical too?

Midorikawa Yes, the functions are the same. However, since the EOS 5D Mark III is not equipped with a 100,000-pixel RGB metering sensor, the AF functions for the position and movement of the subject are controlled based on the output from the AF sensors. The AF system is highly controlled by making statistical predictions, which is the basic logic of AI Servo AF.