The photosensitive element is the "film" of a digital camera. There are two kinds of photosensitive elements: CCD (Charge Coupled) and CMOS (Complementary Metal Oxide Semiconductor). The photosensitive element uses the photoelectric conversion function of photoelectric device to convert the light image on the photosensitive surface into an electrical signal proportional to the light image. Compared with the photosensitive element of "point" light source such as photodiode and phototransistor, the photosensitive element is a functional device, which divides the light image on the light receiving surface into many small units and converts it into usable electrical signals.

The advantage of CCD lies in its good imaging quality. However, due to the complex manufacturing process, only a few manufacturers can master it, and the manufacturing cost remains high, especially the large CCD is very expensive. At the same time, the development of CCD from 300,000 pixels to 6 million pixels has reached its limit. At the same resolution, CMOS is cheaper than CCD, and its power consumption is lower than CCD, but its noise is high.

Sony applied EXMORRCMOS to digital cameras in the spring of 2009. Different from the traditional CMOSEXMOR RCMOS, it puts the photodiode on the top of the image sensor chip and moves the A/D converter and amplifier circuit to the back of the image sensor chip. In this way, it can obtain excellent high sensitivity, and the EXMORRCMOS sensor can read data at a higher speed.