How to buy a camera to see the quality of the lens?

Let's start with the basics. How does the camera work? Light enters from the lens and reaches the photoreceptor. The light sensor converts the light into a digital signal, and then transmits it to a special DSP (digital processing chip) for image processing, and then it can be saved or displayed on the screen, that is, the video we see.

You can't make a good camera without good hardware. There are three magic weapons that determine the quality of a camera: lens, image sensor and digital signal processing chip.

Let's talk about the lens first. Its position in the lens is equivalent to the human eye. Products with cheap plastic lenses are cheaper, and it is recognized that better lenses should be made of glass or fiberglass and composed of multiple lenses. Whether the lens is coated or not is also a factor to evaluate the quality of the lens. How to tell whether the lens is coated? It's simple. Seen from the side, the coated lens has purple or blue-green luster (the refractive color varies according to the coating), while the uncoated lens has no such luster at all.

At present, the photosensitive elements used in mainstream cameras on the market are mainly CCD and CMOS. They are equivalent to the negatives in traditional cameras. CCD has high resolution and vivid color reproduction, and it has become the main character in megapixel digital photographic equipment, but it is expensive. Compared with CCD, CMOS has the characteristics of energy saving and low cost, and the photosensitive effect of CMOS can be completely comparable to CCD within one million pixels, so almost all cameras use CMOS as the photosensitive element. Because China's network bandwidth does not support the smooth transmission of high-definition video, the final screen display effect will not be much different whether the camera uses CCD image sensor or CMOS image sensor. Therefore, there is no need to ask whether the camera uses a CCD image sensor. At present, there are many CMOS brands used in camera products on the market, including Hynix, Micron, OMNIVISION, PIXART, CISENSOR, PIXPLUS, Agilent, ICMEDIA, TASC and other top four brands with a market share of 90%.

Digital signal processing chip DSP is the most important part of the camera. Its function is to transmit the data obtained by the photosensitive chip to the computer in time and quickly, and refresh the photosensitive chip. Therefore, the quality of the control chip directly determines the image quality (such as color saturation and clarity) and fluency. It is also important to have an upgraded driver. The new driver can give it more powerful functions and use effects.

At present, most of the digital signal processing chips used in cameras on the market come from Weiwei. It is said that a media company engaged in product evaluation a few months ago and bought 20 cameras at random in the market. After disassembling, it was found that 19 models were all 30 1P from Weiwei. Hehe, it's awesome. The remaining one is a low-end product with 10 million pixels or not. CMOS sensors from all manufacturers are well matched with ZTE's chips. Zhongxing Micro is the only DSP in the industry that has good support for all CMOS, and it is recognized as a mature solution in the industry. In terms of price, the retail price of ZTE microchip camera products is usually between 100- 150 yuan, depending on the brand, manufacturing process, material selection and application software.

Don't be confused by pixels.

Choosing camera pixels is one of the important indicators to measure the quality of cameras, so businesses often advocate high pixels to win the favor of consumers. So there are some so-called cameras with 450,000 pixels or even 1.3 million pixels on the market. Don't trust these advanced pixels. The identification of these resolutions refers to the interpolation resolution that these products can achieve by using software. Although it can also improve the accuracy of image acquisition, it is still far from the hardware resolution. And for the camera, there is no need for too high pixels at present. The maximum resolution supported by a real 300,000-pixel camera is 640× 480 (640× 480 = 307,200 pixels). Usually, the camera only uses the resolution of 320×240 in application, and the resolution used in network transmission will be lower. Therefore, in the current network bandwidth environment, the practical significance of 300,000 pixels is not great.

Because the camera is mainly used for online chat, and the quality of domestic Internet transmission is not very good, there will be distortion and mosaic after image transmission, and the imaging quality is the most important factor. The quality of a camera depends on its expressive force in various light environments such as low illumination, strong light, and changes in light and shade. Speed is also very important, and the imaging speed mainly depends on the lens configuration of the camera. If it is a glass lens, the imaging speed will be fast, otherwise the plastic lens will be slower. However, it is not advisable for some manufacturers to blindly seek faster transmission speed at the expense of image quality, because the transmission speed of the Internet is much lower than that of cameras, and sacrificing image quality may not be able to achieve faster transmission speed. The quality and speed of the camera are mainly determined by the configuration of DSP. However, users often ignore this link, and usually blindly pursue high pixel and low price while ignoring the overall performance. However, under the current bandwidth conditions, the real 350,000 pixels is enough, and the higher the pixel, the better. In the same picture, the higher the pixels, the stronger the product's ability to analyze images, so the requirements for DSP are much higher. Therefore, when choosing the pixels of the camera, we should adopt the most suitable mainstream products under the current conditions. At present, most of the real 350,000-pixel cameras on the market are equipped with 30 1P chips and glass lenses of ZTE Corporation.

DSP should be the real "core" hero.

Like the CPU in a PC, the "brain" DSP of the camera also plays a vital role in the quality of the camera. So if the "core" is selected correctly, the product is basically selected correctly.

Let's see how the hero behind the scenes works first.

DSP includes three parts: ISP (image signal processor), JPEG encoder (JPEG image decoder) and USB device controller (USB device controller). The function of DSP control chip is to transmit the data obtained by photosensitive chip to the computer in time and quickly, and refresh the photosensitive chip. Therefore, the quality of the control chip directly determines the image quality (such as color saturation and clarity) and fluency. It is also important to have an upgraded driver. The new driver can give it more powerful functions and use effects.

Some DSP vendors have been mentioned above. At present, the DSP with the highest market share is 30 1P and 30 1PL of ZTE Micro, which have good compatibility with various sensors. In addition, it has its own uniqueness in automatic exposure/gain/white balance/color/noise control/gamma correction and dynamic scaling edge antialiasing algorithm, and the image conversion speed is also very fast, which ensures the smoothness of camera images. The 30 1P of zhongxingwei and the 30 1L packaged by 48Pin LQFP are well-known, and their position in the Jianghu can be comparable to that of Intel in the CPU market.