The number of AF points has been increased to 61
When enabling an SLR camera to continuously shoot at higher speeds, would the first issue be controlling the raising and lowering of the mirror?
- Oshima
- In a 35mm full-frame camera, the main mirror linked to the shutter needs to be large and heavy. The sub-mirror, which is located behind the main mirror and sends light to the AF (autofocus) sensor, is also quite heavy. When these two mirrors are operated at high speed, a bounce effect is inevitable. We call this phenomenon "bucking," and it is necessary to stop it to provide stability.
This "bucking" sounds odd. How do you stop it?
- Oshima
- We attached a balancer to efficiently release energy when the mirrors strike, and we enhanced the locking function to securely hold them in place. In the existing product, this mirror bounce prevention mechanism is in two locations, but the 1D X has an enhanced version, which is in four locations. This enables the camera to operate at 12 frames per second. Compared with the 10 frame-per-second continuous shooting speed of the existing model, this is a reduction of just 0.017 seconds per frame, but this difference was huge in terms of the mechanical technology.
Mirror Bounce Prevention Mechanism
- Yoshida
- My team's mission was to ensure the AF operates accurately for each frame, even at 12 frames per second. Moreover, it not only had to be faster than in the past, there was also the added condition of improving AF performance. This performance was achieved by raising the precision of focusing by increasing the number of AF points to 61 from the 45 used in the existing model, while also enabling the focus to track objects based on information received from the AE system. This increase in AF performance required a certain amount of time, so increasing AF speed presented a twofold obstacle.
How did you overcome this?
- Yoshida
- First, by increasing the sensitivity of the AF sensor, we reduced the amount of time that light needs to be held in the element for measuring distance. Furthermore, we adopted a faster AF algorithm and boosted the operation speed of the corresponding circuit. The development of these improvements involved reducing times by thousandths of a second here and there.
Well ... to a layperson, it sounds like it would be enough to make your head spin.
- Ikeda
- The tiniest difference in speed can have a significant effect on specs. Many developers put their heads together for days on end to shave off a thousandth of a second.
DIGIC 4 imaging processor included solely for AE!
- Kashiyama
- Such increases in speed all require power in their respective areas. This is especially true for the mechanical area, which uses motors, but it also applies to the sensors, microprocessors and circuits. However, from the perspective of my team, which was in charge of reducing power consumption, since battery capacity is limited, we wanted to enable the camera to be used as long as possible and to capture as many images as possible, so we couldn't just say, "Yes, please use as much power as you want." The teams in each area fought tooth and nail over power consumption (laughs).
I see. Increased speed is also related to the issue of power consumption. It was mentioned that the AF system and the AE system were linked together. AE has come a long way in the EOS-1D X, hasn't it?
- Yoshida
- Yes, we built a tremendous system. It would've been inconceivable until now, but we included a 100,000 pixel RGB metering sensor, as well as a DIGIC 4 imaging processor just to control the sensor and handle metering and automatic exposure.
That's quite an elaborate setup!
- Yoshida
- I really think so, too. As a result, it's possible to analyze entire images as scenes, and accurately determine exposure by recognizing even colors and people's faces. It's the first time we've ever incorporated this revolutionary new function in a Canon SLR camera.
