Approx. 18.1-megapixel full-frame CMOS sensor
The CMOS sensor and the imaging processor are the two core technologies that hold the key for realizing high sensitivity and high image quality during high-speed continuous shooting, right? First I'd like to ask about the CMOS sensor. What are some of its features?
- Because it is a 35mm full-frame sensor, it has a large light-receiving area, but in addition to that, it utilizes a microlens design to gather light in each pixel without waste. Furthermore, noise has been dramatically reduced through innovations within the internal circuitry to realize rich gradation performance.
- This CMOS features the ability to read out at high speeds despite the high resolution it offers of approximately 18.1 megapixels. Specifically, this was achieved by doubling the number of channels from the number used in the previous model to 16. This is the base that enables high-speed continuous shooting.
What do you mean by channels that read out from the CMOS?
- It refers to a unit for the number of pixels read out in a signal at a single time. In order to achieve high-speed performance, we need to either shorten the processing time required to read the signal from an image, or we need to increase the number of pixels read at once, that is the number of channels for read out. Time time, we succeeded in greatly increasing speed by boosting the number of channels.
I see. Next, I would like to ask you about the DIGIC imaging processor that creates an image based on the signal received from the CMOS. The EOS-1D X has two DIGIC 5+ image processors, right?
- DIGIC 5+ has approximately 17 times the processing power of DIGIC 4. By using two of them in parallel, it's possible to capture high-quality images at 12 frames per second, even at high ISO levels.
Every version of the DIGIC imaging processor offers considerable room for customization, and performs at their best when built upon. Mr. Sugimori, this time around it was your team that focused on this task, right?
- Yes, we worked closely with the team that developed the DIGIC 5+. I'm proud that our team was able to get the most out of the capabilities offered by DIGIC 5+.
- It was a challenge to develop firmware for controlling the imaging system while bringing out the best performance of DIGIC 5+. Compared with the previous model, it feels like we've raised the level of development a few steps.
Working to reduce noise through all possible means
When pursuing high image quality, one factor that must be addressed is noise reduction. Even when using a high-performance low-noise CMOS sensor, noise becomes conspicuous as ISO sensitivity increases. The EOS-1D X's specifications enable image capture at the unbelievably high ISO level of 204800, so noise reduction with DIGIC 5+ must have posed some problems.
- Yes, we made use of a completely new algorithm to deal with noise. Noise reduction in image processing can lead to a soft image with reduced resolution if taken too far, or a rough image if not performed sufficiently. In other words, it's hard to strike the proper balance for noise reduction.
Doesn't electrical circuitry also constantly emit noise that can affect image quality?
- That's right. We were working to increase speed in all areas, so the interior of the camera is filled with sources of noise, such as the microprocessor for controlling mechanisms, the DIGIC image processors, motors, and power supply circuits. The first step we took to address the problem was to consider a layout that would not be affected much by anticipated noise sources. Next, we identified each noise source by conducting repeated tests, and changed components and the layout. We also inserted a filter in response to noise entering via circuit wires, and employed a shielding seal for noise flying through the air. These were about the only physical measures that we could take, as it's impossible to completely eliminate noise. All that was left was to remove the noise with DIGIC 5+.
- There was also the issue of heat generating noise within the CMOS sensor itself. When shooting continuously, the internal temperature steadily rises due to heat from the device. The development team members shared their thoughts and ideas about how to let the heat escape, and we were able to meet our target.