Asking questions about camera parameters

Description of digital camera parameters: the heart of digital camera-photosensitive device. Compared with traditional cameras, traditional cameras use "film" as the carrier of recording information, and the "film" of digital cameras is its imaging photosensitive device, which is integrated with the camera and is the heart of digital cameras. Photoreceptor is the core of digital camera and the most critical technology. The development of digital cameras can be said to be the development of photoreceptors. At present, there are two core imaging components of digital cameras: one is CCD (Charge Coupled Device), which is widely used; The other is CMOS (complementary metal oxide conductor) device. Effective number of pixels is called effective number of pixels in English. Different from the largest pixel, the effective pixel number refers to the pixel value that really participates in photosensitive imaging. The value of the highest pixel is the real pixel of the photosensitive device, and this data usually includes the non-imaging part of the photosensitive device, while the effective pixel is the value converted under the zoom magnification of the lens. The English name of Optical Zoom is Optical Zoom, and digital cameras rely on optical lens structure to achieve zoom. The optical zoom mode of a digital camera is similar to that of a traditional 35mm camera, that is, the scene to be shot is enlarged and reduced by moving the lens. The larger the optical zoom coefficient, the farther the scene is photographed. Digital Zoom, also known as digital zoom, is called digital zoom in English. Digital zoom is to enlarge the area of each pixel in the picture through the processor in the digital camera, so as to achieve the purpose of enlargement. This technology is like enlarging the area of a picture with image processing software, but the program is executed in a digital camera. Some pixels on the original CCD image sensor are enlarged by interpolation, and the pixels on the CCD image sensor are enlarged to the whole picture by interpolation algorithm. Display screen: The biggest difference between digital camera and traditional camera is that it has a screen that can browse pictures in time. The display screen of a digital camera is usually a liquid crystal display. Lens type: The lens of a digital camera consists of multiple lenses, which are made of glass and plastic. If the digital camera lens is made of glass, many users and businesses say that the glass lens has good light transmittance and the projected image is clearer. However, at present, many test reports show that glass lenses do not necessarily bring clearer images than plastic materials, and at the same time, glass lenses may increase the weight of the camera, so you should observe in many aspects when purchasing, and don't stick to the lens materials. The English name of Aperture is aperture. Aperture is a device used to control the amount of light entering the photosensitive surface of the fuselage through the lens. Usually in the camera. The aperture values F2.8, F8 and F 16 are the aperture "coefficients", which are relative apertures, not the physical aperture of the aperture, and are related to the physical aperture of the aperture and the distance from the lens to the photosensitive device (film or CCD or CMOS). Aperture: The smaller the f value of the aperture, the more light enters per unit time, and the amount of light entering at the upper level is exactly twice that of the lower level. For example, if the aperture is adjusted from F8 to F5.6, the amount of light entering will double. We also say that the aperture is enlarged by one level. Most non-professional digital camera lenses have short focal length and small physical aperture, and the physical aperture of the aperture is already very small in F8. If it continues to shrink, optical phenomena such as diffraction will appear, which will affect imaging. Therefore, generally speaking, the minimum aperture of a non-professional digital camera is from F8 to F 1 1, while the photosensitive device of a professional digital camera has a large area, and the lens is far away from the photosensitive device, so the aperture value can be very small. For consumer digital cameras, the aperture f value is often between F2.8-F 16. In addition, many digital cameras can adjust the aperture by 1/3. Shutter, whose English name is Shutter, is a device on camera to control the effective exposure time of photosensitive film. The working principle of the shutter is as follows: in order to protect the photosensitive device in the camera from exposure, the shutter is always closed; When shooting, after adjusting the shutter speed, just press and hold the shutter release button of the camera (that is, the camera button), so that the light passing through the camera lens can be correctly exposed between the opening and closing of the shutter, and the light can enter the photosensitive device through the shutter and be written into the memory card. As for the common B shutter function of SLR cameras, although you can freely decide the length of exposure time and have high shooting flexibility, most consumer digital cameras can't support it at present, and can provide the default values of slower speed such as 2 seconds, 8 seconds, 16 seconds at most. A perfect shutter usually has the following functions: first, it must have the function of accurately adjusting the exposure time, which is the most basic function of camera shutter; Second, the shutter speed must be high enough to shoot high-speed motion or effectively control the depth of field; Third, it must have the function of long-term exposure, that is, it must be equipped with a "T" door or a "B" door; Fourth, it has the function of flash synchronous shooting; Fifth, it has a self-timer function, which can open the shutter without releasing the cable during self-timer or long exposure. The English scientific name of flashlight is flashlight. Flash is also one of the ways to enhance exposure, especially in dim places, which helps to make the scenery brighter. There are also disadvantages to using flash. For example, when shooting people, the light of the flash may remain in the pupil of the eye, and then "red eye" will appear. Therefore, many camera manufacturers have added the function of "eliminating red eye" in their designs, and before turning on the flash, they will emit weak light to adapt to the pupil, and then carry out real flash to avoid red eye. Generally, there are three flash modes for middle and low-grade digital cameras, namely, automatic flash, red eye removal and off flash. More advanced products also provide "forced flash" or even "slow flash" function. The English name of White Balance is white balance. The color of the object will change due to the color of the projected light, and the photos taken under different light conditions will have different color temperatures. For example, a photo taken under the illumination of tungsten lamp (light bulb) may be yellow. Generally speaking, CCD can't automatically correct the change of light like human eyes. The English name of the continuous shooting function is continuous shooting, which captures the shooting opportunity by saving data transmission time. Continuous shooting mode can take multiple photos in a short time by loading the data into the high-speed memory (cache) inside the digital camera instead of transferring the data to the memory card. Because digital cameras have to go through photoelectric conversion, a/d conversion and media recording, both conversion and recording take time, especially recording takes time. So the continuous shooting speed of all digital cameras is not very fast. The short film shooting function means that the digital camera has the function of shooting video files. Unlike DV (Digital Camera), digital cameras can only store video files in memory cards. Due to the limited memory space, the quality and size of video files are relatively poor. The recording function is the function of recording through the microphone on the digital camera. Because it is not a professional video camera or recorder, the audio recorded by digital camera is mono. The recording functions of digital cameras can be roughly divided into three types: live short film recording, voice file annotation and pure recording. Storage medium: Digital cameras convert image signals into data files and store them on magnetic media devices or optical recording media. If the digital camera is the host of the computer, then the memory card is equivalent to the hard disk of the computer. The memory can record not only image files, but also other types of files. It is connected with the computer through USB and becomes a mobile disk. Common storage media in the market include CF card, SD card, MMC card, SM card, memory stick, xD card, MICRoDRIVE and so on. Scene mode: Generally speaking, the aperture, shutter, focal length, metering mode, flash and other parameters of a digital camera are adjusted in advance, so that inexperienced users can take digital photos with certain quality assurance. However, using the existing mode may not be able to take high-quality photos. A considerable number of friends use the AUTO mode of digital cameras, but in a specific shooting environment, the quality of their photos is of course difficult to guarantee. Therefore, in order to make it more convenient for beginners to use, digital camera manufacturers have added several scene modes to their digital cameras, making it easier to take high-quality photos. At present, there are as few as four or five scene modes of digital cameras as twenty or thirty. Battery: Digital cameras need batteries to maintain normal operation. Generally speaking, digital cameras can use dry batteries, alkaline zinc-manganese batteries, cadmium-nickel batteries, nickel-hydrogen batteries, lithium-ion batteries and lithium batteries as power sources. The noise of digital camera, also called noise, mainly refers to the rough part of the image when CCD(CMOS) receives and outputs light as the received signal, and also refers to the foreign pixels that should not appear in the image, usually caused by electronic interference. It looks like the image has been dyed and covered with some tiny rough spots. The digital photos we usually take may not be noticed if we use a personal computer to reduce the high-quality images and then look at them. However, if the original image is enlarged, there will be a color (pseudo-color) that did not exist originally, and this pseudo-color is image noise. References:

Thanks to IT 168.