The image sensor is the core and most critical technology of digital cameras. In traditional cameras, film is a kind of photosensitive material. After a certain chemical treatment, it will record the captured images. Film is already past tense, in a digital camera, an image sensor instead of film locations, the formation of electronic images.
There are two types of image sensors that we can see on the market: charge coupled device image sensor CCD (Charge Coupled Device) and complementary metal oxide semiconductor CMOS (Complementary Metal-Oxide Semiconductor) (hereinafter referred to as CCD and CMOS )
Both use photodiodes for photoelectric conversion to convert images into digital data. The main difference is the method of digital data transmission and the manufacturing process.
The difference between CCD and CMOS
CCD is a semiconductor component, invented by Bell Laboratories in the United States in 1970. CCD is actually a group of photoelectric bodies that can perform “photoelectric conversion”. When light is focused by the lens to form an image, the CCD will convert the light signal of the image into an electrical signal (voltage). The greater the amount of light, the greater the number of electrons released, the stronger the electrical signal, and the brighter the pixel display.
CMOS and CCD are the same semiconductors that can record light changes in digital cameras. The manufacturing technology of CMOS is no different from that of general computer chips. It mainly uses semiconductors made of silicon and germanium to make it coexist with N (charged-charged) and P (charged + charged) grades on CMOS. In semiconductors, the current generated by these two complementary effects can be recorded and interpreted into images by the processing chip.
Is it confused? Actually, you don’t need to memorize it, just remember one point. Each pixel of the CCD sensor is a separate photoelectric body, and the accuracy of recording image information is higher than that of CMOS.
Advantages of CCD
1. High imaging quality . The light utilization efficiency, dynamic range and sensitivity of CCD are better than CMOS, and its resolution is also higher than CMOS.
2. Low noise . The electrical signals output by different image-sensitive units in the CCD are uniformly amplified, and the noise is lower than that of CMOS. It is difficult for CMOS to guarantee the consistency of the magnification of all amplifiers, so it is more likely to cause uneven pixel response and cause a lot of noise in the picture.
Advantages of CMOS
1. The transmission rate is fast . The CMOS sensor can take out the electrical signal while collecting the light signal, and can process the image information of each unit at the same time, and the transmission speed is much faster than that of the CCD. The CCD needs to output information bit by bit in line units under the control of a synchronized clock, which is slower.
2. Low cost . CCD requires special manufacturing equipment, and the damage of one unit will cause the entire column to be scrapped, so its yield is low, and the production cost and technical threshold are high.
3. Low consumption . CCD needs an external voltage to move the charge, and different vertical registers require different voltages, so a dedicated power management circuit is required. Therefore, the power consumption of the CCD is higher than that of the CMOS of the same size.
The image quality of CCD is better than that of CMOS. CMOS is less difficult to produce, low cost, and low power consumption. Every photographer can choose according to their needs.
In order to lower the cost, most manufacturers choose CMOS sensors with inferior effects. Only in this way can we buy SLR or mirrorless cameras at a lower price.
Sensor into the gray it is because the photoelectric conversion process camera sensor, so with static electricity on the low-pass filter sensor , this lens will absorb dust, in fact, vendors have made anti-static treatment, but it has a little static electricity are still Unrealistic, this is the same as gray on old CRT TVs.
When faced with the sensor of choice is dust that comes with the camera sensor cleaning function
If the camera comes with the program does not work, then you can try blowing method , because this method also can not come into contact with the sensor, is absolutely safe. Local tyrants can buy special compressed air to blow.
Finally, if you are a photographer who is not very familiar with the camera structure, try not to use the latter two methods in terms of sensor cleaning. The sensor itself is brittle, and once scratched, it will cause immeasurable loss. Therefore, when the photo appears dusty, it can be handled by professionals or after-sales.