2026-07-28
The length of the focal length of the lens determines the size of the image taken, the size of the field of view, the size of the depth of field and the perspective strength of the picture. Generally speaking, for a single-lens lens, it is the distance from the center of the lens to the focus, while a camera lens is composed of multiple lenses, which is much more complicated. The focal length here refers to the distance from the center point of the lens to the clear image formed on the photosensitive device (CCD).
We often use the horizontal field of view to reflect the shooting range of the picture. The larger the focal length f, the smaller the field of view, and the smaller the range of the picture formed on the photosensitive element; conversely, the smaller the focal length f, the larger the field of view, and the larger the range of the picture formed on the photosensitive element.
F value refers to the brightness of the lens (that is, the amount of light transmitted by the lens). F=lens focal length/aperture diameter. For the same F value, the diameter of a long focal length lens is larger than that of a short focal length lens.
The aperture is an adjustable optical-mechanical aperture located inside the lens, which can be used to control the amount of light passing through the lens. Variable aperture (Iris diaphragm). A mechanical device inside the lens used to control the size of the aperture. Or refers to a device used to open or close the lens aperture to adjust the f-stop of the lens.
When an object is in focus, all objects from a certain distance in front of the object to a certain distance behind it are also in focus. The distance from front to back where the focus is quite clear is called depth of field.
The full name is Voice Coil Montor, a voice coil motor in electronics, which is a type of motor. Because the principle is similar to that of a speaker, it is called a voice coil motor, which has the characteristics of high frequency response and high precision. Its main principle is to control the stretching position of the spring leaf by changing the DC current of the coil in the motor within a permanent magnetic field, thereby driving up and down movement. Mobile phone cameras widely use VCM to achieve autofocus function. VCM can adjust the position of the lens to present clear images.
The performance of VCM mainly depends on the ratio of current and travel distance. Starting from the starting current, the current rise must be proportional to the driving distance. The smaller the required rising current, the higher the accuracy. It also depends on the maximum power consumption, maximum power, and size.
The structure can be roughly divided into three categories:
Functionally, it can be roughly divided into five categories:
After entering the auto-focus mode, the Driver moves from 0 to the maximum value, causing the lens to move from the original position to the maximum displacement. At this time, the sensor imaging surface automatically captures pictures and saves them to the DSP. The DSP uses these pictures to calculate the MTF (Modulation Transfer Function) value of each picture to find the maximum value in this MTF curve. Through the algorithm, the current size corresponding to this point is obtained, and the Driver is again instructed to provide this current to the voice coil, so that the lens is stabilized on this imaging surface, allowing automatic zooming.
By moving the lens inside the lens, the position of the focus is changed, the focal length of the lens is changed, and the angle of view of the lens is changed, thereby amplifying and reducing the effect.
By moving the position of the entire lens (rather than the lens within the lens) at a micro distance, you can control the focal length of the lens to achieve a clear image. A commonly used method in mobile phones.
Optical focus and optical zoom are different concepts:
Optical zoom changes the position of the focus by moving the relative position of the lens inside the lens, changes the focal length of the lens, and changes the angle of view of the lens, thereby enlarging and reducing the image; optical focusing actually adjusts the position of the entire lens (rather than the position of the lens within the lens) to control the image distance, thereby making the image the clearest.
There are various wavelengths of light in nature. The wavelength range of light recognized by the human eye is between 320nm-760nm. The human eye cannot see light exceeding 320nm-760nm. The camera's imaging component CCD or CMOS can see most wavelengths of light. Due to the participation of various lights, there is a color deviation between the color restored by the camera and what is seen by the naked eye. For example, green plants turn gray, red pictures turn light red, black turn purple, etc. At night, due to the filtering effect of the bimodal filter, the CCD cannot make full use of all light, does not produce snowflake noise, and its low-light performance is unsatisfactory. To solve this problem, use the IR-CUT dual filter.
IR-CUT dual filters refer to a set of filters built into the camera lens set. When the infrared sensing point outside the lens detects changes in light intensity, the built-in IR-CUT automatic switching filter can automatically switch according to the intensity of external light to achieve the best image effect. In other words, the dual filters can automatically switch filters during the day or night, so you can get the best imaging effect regardless of the day or night.
The IR CUT dual filter switcher consists of an infrared cut-off low-pass filter (an infrared cut-off or absorption filter), a full-spectrum optical glass (a full-spectrum transmittance filter), a power mechanism (can be an electromagnetic, motor or other power source) and a housing. It is switched and positioned through a circuit control board. When there is sufficient light during the day, the circuit control board drives the switch to switch and position the infrared cut-off filter to work, and the CCD or CMOS restores the true color; when the visible light is insufficient at night, the infrared cut-off filter automatically moves away, and the full-spectrum optical glass starts to work. At this time, it can sense the infrared light of the infrared lamp, allowing the CCD or CMOS to make full use of all the light, thereby greatly improving the night vision performance of the infrared camera, and the entire picture will be clear and natural.
Generally, IR Coating or blue glass is used to filter out infrared light.
Image sensor is a semiconductor chip with millions to tens of millions of photodiodes on its surface. The photodiodes generate charges when exposed to light and convert light into electrical signals. Its function is similar to the human eye, so the performance of the sensor will directly affect the performance of the camera.
Photosensitive original: CCD, CMOS (PPS and APS)
Different processes: front-illuminated FSI, back-illuminated BSI, stacked
There are many photosensitive units on the sensor, which can convert light into electric charges to form an electronic image corresponding to the scene. In the sensor, each photosensitive unit corresponds to a pixel (Pixels). The more pixels, it means that it can sense more object details, so the image is clearer. The higher the pixels, the clearer the imaging effect. The product of camera resolution is the pixel value, for example: 1280*960=1228800
The size of the photosensitive part of the image sensor, generally expressed in inches. Like TVs, this data usually refers to the diagonal length of the image sensor, such as 1/3 inch. The larger the target surface, the better the light transmission, and the smaller the target surface, the easier it is to obtain a greater depth of field.
That is, the intensity of incident light is sensed through CCD or CMOS and related electronic circuits. The higher the sensitivity, the stronger the sensitivity of the photosensitive surface to light, and the higher the shutter speed. This is especially important when shooting sports vehicles and monitoring at night.
A term coined in reference to the mechanical shutter function of a camera. It controls the photosensitivity time of the image sensor. Since the photosensitivity value of the image sensor is the accumulation of signal charges, the longer the photosensitivity, the longer the signal charge accumulation time, and the greater the amplitude of the output signal current. The faster the electronic shutter, the lower the sensitivity, which is suitable for shooting under strong light.
It refers to the number of pictures recorded or played per unit time. Continuously playing a series of pictures will produce an animation effect. According to the human visual system, when the picture playback speed is greater than 15 frames/second (i.e. 15 frames), the human eye will basically not be able to see the jump of the pictures; when it reaches 24 frames/s - 30 frames/s (i.e. 24 frames to 30 frames), the flicker phenomenon will be basically undetectable.
Frames per second (fps), or frame rate, represents the number of times a graphics sensor can update per second while processing a field. A high frame rate results in a smoother, more realistic visual experience.
It is the ratio of signal voltage to noise voltage, and the unit of signal-to-noise ratio is expressed in dB. Generally, the signal-to-noise ratio values given by cameras are the values when AGC (automatic gain control) is turned off, because when AGC is turned on, small signals will be increased, causing the noise level to increase accordingly.
The typical value of the signal-to-noise ratio is 45-55dB. If it is 50dB, the image has a small amount of noise, but the image quality is good; if it is 60dB, the image quality is excellent and there is no noise. The larger the signal-to-noise ratio, the better the control of noise. This parameter is related to the number of noise points in the image. The higher the signal-to-noise ratio, the cleaner the picture feels, and the less point-like noise in the night vision picture.
Digital signal processor DSP (DIGITAL SIGNAL PROCESSING) function: mainly through a series of complex mathematical algorithm operations, optimize the digital image signal parameters, and transmit the processed signal to PC and other devices through USB and other interfaces
ISP is the abbreviation of Image Signal Processor, which is also the image signal processor.
DSP is the abbreviation of Digital Signal Processor, which is also a digital signal processor.
ISP is generally used to process the output data of Image Sensor, such as AEC (automatic exposure control), AGC (automatic gain control), AWB (automatic white balance), color correction, Lens Shading, Gamma correction, removal of bad pixels, Auto Black Level, Auto White Level and other functions.
DSP has more functions. It can do photography and echo (JPEG codec), video recording and playback (Video codec), H.264 codec, and many other aspects of processing. In short, it processes digital signals.
UVC, the full name of USB Video Class, is a set of standards customized by USB-IF. All USB interface cameras that follow this standard can be used almost directly under systems such as Windows and Linux, achieving similar driver-free effects.
Of course, this does not mean that there need not be a driver, but as long as a camera with a USB interface complies with the UVC standard, it can be driven by a common set of drivers in Windows and Linux systems, without the need for you to install other drivers. For example, there is a set of universal drivers for UVC devices in the Linux kernel: drivers/media/usb/uvc. As long as this set of drivers is turned on, almost all UVC cameras can be used directly.
MIPI (Mobile Industry Processor Interface) is the abbreviation of Mobile Industry Processor Interface. MIPI is an open standard for mobile application processors initiated by the MIPI Alliance.
The MIPI organization is committed to standardizing interfaces within mobile communication devices to reduce compatibility issues and simplify design. For example, camera interface CSI, display interface DSI, radio frequency interface DigRF, microphone/speaker interface SLIMbus, etc.
DVP interface: Parallel port transmission, slow speed, low transmission bandwidth, use requires PCLK\sensor output clock, MCLK (XCLK)\external clock input, VSYNC\field synchronization, HSYNC\line synchronization, D[0:11]\parallel port data-can be 8/10/12bit data bit size.
LVDS interface: LVDS (Low Voltage Differential Signaling) is low voltage differential transmission
Network port: IPC web camera
SDI interface: a professional video interface that uses coaxial cables and uses digital signals. There are now 18GHz bandwidth products that can meet 8K video transmission.
RGB interface: Analog video interface, using coaxial cable, taking analog signals, below 720x576 standard definition signal.
eDP interface: a relatively new specification, which will be widely used to replace LVDS in the notebook industry. It supports ultra-high resolution and supports 1080P or above.
