Surveillance camera shooting

The TV monitoring system can directly watch what happens in the monitoring place and target on the monitor through remote control of cameras, lenses, electric pan-tilt and other equipment. And transmit the image information content of the monitored place and target to a video recorder for recording.

Camera: converts the optical signal of the subject into electrical signal, and then sends it to the transmission part of the system for transmission.

CCD black-and-white and color cameras should be selected as cameras. The horizontal resolution of black-and-white camera is ≥400 lines, and the horizontal resolution of color camera is ≥270 lines. Signal-to-noise ratio should be ≥46dB. Cameras with different sensitivities should be selected according to the illuminance of the monitored object. The minimum ambient illumination of the monitored object should be 10 times higher than that of the camera. When remote control is needed, you can choose a remote control lens device with optical focusing, aperture opening and zoom. The camera can be a charge coupled device (CCD) camera, which is small in size, light in weight and convenient for field installation and maintenance. According to the working environment, select the corresponding camera protective cover. The protective sleeve can be equipped with temperature control system and remote wiper as required. The supporting device for fixing the camera at a specific position can adopt a camera bracket or a tripod head. When the camera needs to monitor multiple scenes in different directions, it should be equipped with automatic focusing device and remote control electric pan/tilt. When the camera needs to be hidden, it can be set on the ceiling or wall, and the lens can be pinhole or prism lens. For the anti-theft system, additional external sensors and system combinations can be installed for linkage alarm. The system and equipment for monitoring underwater targets should adopt high-sensitivity camera tube, sealed pressure-resistant waterproof protective sleeve and water seepage alarm device. The setting position, shooting direction and lighting conditions of the camera shall meet the following requirements:

(1) The camera should be installed near the monitoring target where it is not easy to be damaged by the outside world, and the installation position should not affect the operation of field equipment and the normal activities of personnel. The indoor installation height should be 2.5 ~ 5m from the ground, and the outdoor installation height should be 3.5 ~ 10m, and not less than 3.5m. ..

(2) The camera in the elevator car should be installed at the top of the elevator car and on the diagonal of the elevator operator, and can monitor the panoramic view in the elevator car.

(3) The camera lens should avoid direct strong light to ensure that the target surface of the camera tube is not damaged. Within the field of view of the lens, there should be no object blocking the monitoring target.

(4) The camera lens should be aimed at the monitoring target from the light source direction to avoid installing backlight; When the backlight needs to be installed, the contrast of the monitoring area should be reduced.

Cameras: There are two kinds of cameras: color cameras and black-and-white cameras. Camera target specifications are: 1 inch, 1/2 inch, 2/3 inch, 1/3 inch, etc. (1) The camera should be installed near the monitoring target where it is not easy to be damaged by the outside world. Installation height: 2.5 ~ 5m indoor from the ground, 3.5 ~ 10m outdoor from the ground, and not less than 3.5m. ..

(2) The camera in the elevator car should be installed at the top of the elevator, on the diagonal of the elevator operator; The optical axis of the camera forms a 45-degree angle with the two walls of the elevator and a 45-degree depression angle with the ceiling of the elevator.

(3) The camera lens should aim at the monitoring target along the light source direction.

(4) The camera lens should avoid direct glare to ensure that the target surface of the camera tube is not damaged; There must be no object in the field of view of the lens to block the monitoring target.

See 97×700 Atlas of Weak Current Engineering Design and Construction of Intelligent Buildings for details. First, the maximum aperture

The real value of the maximum aperture is to increase the amount of light entering in weak light, so as to achieve the best exposure combination. Shooting scenery generally does not require the blur ability of the lens, and in addition, except for particularly dark places, the requirements for lens caliber are generally not too high. However, when the 70-200 mm zoom lens is matched with the 2x zoom lens to make the telephoto lens reach 400mm and focus automatically, it is best to choose the lens with the maximum aperture of F2.8, which is conducive to accurate focusing in dark conditions. Shooting people with a large aperture lens can shoot natural light with a mobile phone even in weak light. In addition, the lens with the largest aperture can bring faster shutter speed, so sports photography also needs a large aperture lens.

Another reason for requiring a large lens aperture is to freely blur the background to ensure the blur quality. When the aperture of the lens with the maximum aperture of F 1.4 is reduced to F2, both the imaging quality and the background blur quality are better than those of the lens with the maximum aperture of F2. Therefore, it is very valuable to reduce the aperture by one step with a large aperture lens, and any photographer should be good at using this feature of the lens.

Second, the focal length.

The first thing to pay attention to when choosing a lens is the focal length of the lens. The focal length is actually a matter of viewing angle, and different focal lengths have different viewing angles. In addition, users should be clear about themselves, what is the main purpose of my purchase of lenses? Whether to shoot scenery or people, and so on. As we all know, it is advisable to use a wide-angle lens to shoot landscapes and a telescope lens to shoot people. Therefore, we must first decide the lens focal length we want to buy according to the purpose of photography.

The best focal length for shooting scenery is 24mm wide-angle focal length and 200mm telescopic focal length (both are subject to 35mm specifications, the same below). When the wide-angle focal length of the standard zoom lens evolves from 28mm to 24mm, the viewing angle becomes larger and the range of scenery that can be accommodated is greatly broadened. Generally speaking, the maximum aperture of the lens is not too high for shooting scenery. If you mainly shoot scenery, when choosing a zoom lens, it is basically enough to choose a wide-angle focal length of 24 mm. As for the focal length of the telescope, it should be at least 200 mm. If the focal length of the telescope is 300mm or 400mm, it will be more ideal, and the degree of freedom will be greatly improved. The telephoto focal length of the traditional zoom lens is 300mm, while it is 450mm when used in digital SLR, and the focal length is enlarged by 1.5 times, which makes people feel happier when used. This is the value of digital SLR. Generally, the wide-angle focal length of digital special ultra-wide-angle lens is 12mm, which is equivalent to 18mm of 35mm specification, which is nearly 1.5 times larger than the focal length of 28mm of 35mm specification, thus greatly broadening the left and right range of shooting landscape scenes.

The best focal length for shooting people is 85 mm. According to the standard of 35mm, the lens is selected based on the focal length of 85 mm.. The portrait taken with a focal length of 85mm is basically close to the picture taken by a medium format camera, which not only has a suitable sense of distance, but also the face of the person looks natural, and the distance between the camera and the subject can basically be kept at the usual speaking distance. 85mm focal length can also blur prominent people in the background. In order to obtain a good blur effect, it is appropriate to choose a lens with a larger maximum aperture. The focal length of 85mm is about 135mm on a digital SLR. Although the distance of the lens is a little weak, it is basically no problem, so the focal length of the lens should be at least about 85 mm

A macro lens of 100mm is enough for traditional SLR. 100mm macro lens can shoot flowers at the same time, but when shooting at the same time or near the same time, it is easy to shake because of the long focal length and depth of field of the scene, so anti-shake measures should be considered when shooting. From this point of view, it is easier to use a 50mm macro lens on a digital SLR.

Third, close-up ability

The close-up ability of the lens is another key point after the focal length and the maximum aperture. The same is true for wide-angle lenses, standard lenses and telescope heads. So, how big is the close-up ability?

First of all, the close-up ability of a wide-angle lens has almost nothing to do with the wide-angle lens, but when shooting a flower scene with a vast landscape as the background, it is often necessary to shoot the flowers a little bigger. In similar circumstances, the close-up ability of a wide-angle lens is very important.

The close-up capability of the existing 50mm standard lens is about 45cm, which basically meets the use. However, when the shortest shooting distance is used, the large-aperture standard lens often produces large aberration because of the lens protrusion, resulting in low imaging quality. We should be prepared for this when buying and using.

If you use a telescope to shoot scenery, there is not much requirement for close-up ability. But if it is used to shoot people or flowers, the close-up ability of the lens is very important.

Fourth, expressive force.

When many people choose a lens, the first concern is the clarity of the lens. The purpose of the photo determines what kind of sharp lens is needed. High-priced high-quality lenses are mainly used by professional photographers. If it's just general photography, there's no need to spend a lot of money on expensive and high-quality lenses. In addition, the imaging clarity of the lens is directly related to the aperture size. When a lens is reduced by one or two steps from the maximum aperture, the imaging clarity will be greatly improved.

Distortion is an optical phenomenon caused by the optical properties of lenses. It's impossible that every shot has no distortion. Manufacturers have corrected the distortion when producing lenses, trying to control the distortion to the lowest level. Generally speaking, there are three kinds of lens distortion: barrel distortion at the wide-angle end of zoom lens, pincushion distortion at the telephoto end and hat distortion after barrel distortion correction at the wide-angle end. As far as the current situation of lens is concerned, the most prominent problem is the barrel distortion at the wide-angle end. Try to choose a style with small barrel distortion when purchasing.

In backlight photography, halos and light spots will be formed on the screen due to the repeated reflection of strong sunlight or other strong light sources on the mirror. This small part of the light that forms halo and flare will not only be imaged on the screen, but also form random reflection in the mirror, which will reduce the imaging quality. In order to prevent this phenomenon, backlight photography must use a hood. Excellent lens adopts the process of completely preventing halo and glare in the manufacturing process, and the contrast is good even if it is shot in reverse light. 1. Turn on the automatic electronic shutter function of the camera.

2. Adjust the lens aperture to the maximum with the controller.

3. Aim the camera at an object 30 meters away and adjust the focal length to infinity (most of the lenses are facing the lens.

The focus adjustment ring rotates clockwise to the bottom)

4. Use the controller to adjust the zoom of the lens to push the scene farthest, and adjust the intercept behind the lens to make the scene clearest.

5. Use the controller to adjust the zoom of the lens to pull the scene, and fine-tune the focal length of the lens to make the scene clearest.

6. Repeat steps 4-5 several times until the scene is always clear when the lens is zoomed.

CCD cameras can be roughly divided into the following categories:

Divided by camera resolution

The image is above 380,000 points, the color resolution is greater than or equal to 480 lines, the black-and-white resolution is above 600 lines.

Divided by camera sensitivity

(1) Normal type: the illumination required for normal operation is 1~3 lux.

(2) Moonlight type: the illumination required for normal operation is about 0. 1 lux.

(3) Starlight type: the illumination required for normal operation is below 0.0 1 lux.

(4) Infrared illumination type: In principle, the illumination can be zero, and infrared light source is used for imaging.

According to the size of the CCD target surface of the imaging element

(1) The size of the 2/3-inch target surface is 8.8mmX wide, 6.6mm high and 1 1 mm diagonal.

(2) The size of the target surface 1/2in is 6.4 mm wide, 4.8 mm high and 8 mm diagonal.

(3) The dimensions of1/3 inch target surface are: 4.8mmX in width, 3.6mm in height and 6mm in diagonal.

(4) 1/5in is under development, and the formal product features have not yet been introduced:

1. 1/3 "Sony CCD high-definition infrared color camera

2. 12 adopts imported IR LED lamps, and projects light sources from different angles to make the image clearer.

3. Turn on the infrared automatically when the light is lower than 10Lux; The shooting distance exceeds 15m.

4. Adopt imported lens to prevent moisture from affecting the image.

5. Plane wall mounting /90-degree corner mounting two shapes.

Infrared camera technology is divided into passive infrared camera technology and active infrared camera technology. The principle of passive infrared camera technology is that any object will emit infrared light above absolute zero (273℃). Because the infrared light emitted by human body and heated objects is strong, and the red light emitted by other non-heated objects is weak, special infrared cameras can be used to realize night monitoring. Passive infrared camera technology is not used in night vision system because of its high equipment cost and inability to reflect the surrounding environment. Active infrared camera technology uses a special "infrared lamp" to artificially generate infrared radiation that is invisible to human eyes but can be captured by ordinary cameras to "illuminate" the scenery and environment, and use ordinary low-illumination CCD black-and-white cameras or cameras that automatically change color to black and white during the day and night or infrared low-illumination color cameras to feel the surrounding environment.

Reflect infrared light, thus realizing night vision function.

Light is an electromagnetic wave with a wavelength ranging from a few nanometers (1nm= 10-9m) to 1 mm (mm). What is visible to the human eye is only a part of it, which we call visible light. The wavelength range of visible light is 380 nm to 780 nm. Visible light can be divided into red, orange, yellow, green, blue and purple light from long to short. The wavelength shorter than violet light is called ultraviolet light, and the wavelength longer than infrared light is called infrared light.

Infrared camera is a camera equipment which integrates camera, protective cover, infrared lamp, power supply and heat dissipation unit. The basic principle of night vision is that ordinary CCD black-and-white camera can feel the spectral characteristics of infrared light (that is, it can feel both visible light and infrared light), and cooperate with infrared lamp as "lighting source" to carry out night vision imaging. Explosion-proof camera

Product name:

B-class carbon steel (30m-80m) explosion-proof infrared camera.

Parameter characteristics:

Class B or C explosion-proof, color 420-wire or 480-wire, 30m-80 infrared lamp automatically turned on, 1/3 "Sony Exview CCD, lens focal length optional, special carbon steel stainless steel optional, IP65, built-in radiator, direct power supply of 220V (36 and 8 infrared lamps).

Explosion-proof camera has the function of nano invisible wiper (no water, no oil and no dust).

Place of application:

It is suitable for monitoring dangerous places such as petrochemical industry, mines, military industry, medicine, ammunition depots, explosives depots, oil depots, ships, drilling platforms, gas stations, fireworks production, grain processing and storage, oil tankers, oil tankers, small warehouses and explosion-proof elevator.