What is the principle of camera telephoto technology?

Working principle and usage of video camera

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Working principle and usage of video camera

The camera is a device that converts the light image of the subject into TV signal, and it is the main signal source of TV programs and TV teaching materials.

◆ Type of camera

Cameras can be divided into analog and digital according to signal processing methods.

According to the different color conversion methods, it can be divided into three CCD and single CCD. General professional or broadcast level with three CCD cameras; Single-chip CCD cameras are used for home and mass use.

◆ Main technical indicators of the camera

The main performance of the camera is determined by the following technical indicators:

Clarity: mainly determined by the number of pixels of CCD chip. Generally, the number of pixels of a single CDD is 800,000 ~ 2 million, while the number of pixels of three CCDs is 400,000 ~ 6.5438+00,000. Image sharpness refers to the camera's ability to decompose black and white thin lines. General household cameras have a resolution of 400-500 lines, and broadcast cameras have a resolution of 600-800 lines. The more stripes are decomposed, the higher the definition of the image.

Sensitivity: It is mainly related to the area of CCD chip and the aperture of lens. Generally, the chip of broadcast camera is 1/2 inch to 2/3 inch, with high sensitivity, while the chip of home camera is 1/6 inch to 1/4 inch, with low sensitivity. Usually, under the irradiation of standard light source, the camera shoots the test card, and the smaller the aperture used for the output to reach the standard value, the higher the sensitivity of the camera. The aperture value of general broadcast cameras is F8-F 1 1, and that of home cameras is F4-F5.6 ..

Minimum illumination: The minimum illumination refers to the illumination required for comparing shooting scenes under a certain signal-to-noise ratio. The lower the illumination, the higher the camera sensitivity. The minimum illumination of the camera can reach 0.5Lux.

Color reproduction: indicates the fidelity of color pictures taken by the camera. Generally, the color reproduction of 3 CCD camera is better than that of single CCD camera.

There are other indicators of the camera, such as geometric distortion, coincidence accuracy, degree of automation, shock and vibration resistance, working environment temperature range, multifunctional signal interface, convenient operation and so on. These are all factors to consider when choosing. ◆ Use and maintenance of camera

The use of cameras

Before the camera is officially used, check whether the switches are placed in the required positions. Then turn on the switch, and after a few seconds, the viewfinder will light up. After the image viewfinder appears, open the lens cover and make various adjustments.

Focus adjustment. Focus adjustment should ensure that the zoom of the wide-angle (W) to telephoto (T) lens can make the image of the scene clear. Therefore, firstly, set the aperture to the automatic position (a), take a close-up image (t) of the scene with a long focal length, and adjust the focus ring of the lens to make the image clear; Then shoot the wide-angle image (W) of the scene with a short focal length to ensure that the image is always clear when zooming.

Zoom control. There are two ways to change the focal length of the lens: electric and manual. Generally speaking, when shooting with a push-pull lens, electric zoom is often used to change the speed smoothly, and manual zoom should be used when shooting with fast zoom or special effects.

Color filter adjustment. The color filter of the camera includes two kinds of neutral color filters and color temperature correction plates with different properties. Install them.