In winter, the climate is cold. In order to prevent the body from freezing, antifreeze can be added to the cooling system of the engine. The common antifreeze liquids on the market are: ethanol, glycerol - ethanol, glycerol, ethylene glycol, etc. These antifreezes have different freezing points due to their different formulation ratios and compositions. The freezing point of routinely selected antifreeze should be lower than the local minimum temperature of 10°C to prevent the temperature from exceeding the icing point of the antifreeze and rendering the antifreeze liquid ineffective. Use antifreeze also pay attention to the following points: One is to remove the scale of the cooling system before adding the antifreeze solution, and drain the residual water at a time to prevent the accumulated water from diluting the antifreeze solution and reducing the freezing and freezing point of the antifreeze solution. The second is that when antifreeze is added, it can only be added within 95% of the capacity of the cooling system. Antifreeze has hygroscopicity and should be sealed in time after use. Third, ethanol and ethylene glycol antifreeze all have certain toxicity. They must not touch the surface of the skin, nor can they be sucked by the mouth. Ethylene glycol is an organic solvent and should not be dripped or sprinkled on the surface of the body during filling to prevent the paint from rusting. Ethylene glycol and glycerol will reduce the volumetric volume due to volatilization. Add water in time and add antifreeze of the same type, the same type, and the same freezing point after leakage. Fourth, ethanol, glycerol - ethanol antifreeze, the contained alcohol are volatile and flammable, pay attention to fire prevention. If the degree of alcohol is reduced by volatilization, it can be supplemented with 80% ethanol and 20% water. All kinds of different types, different types, different freezing point antifreeze can not be mixed and mixed. Camera Kits System With 8 Camera The intelligent analysis of intelligent high-definition cameras is mainly aimed at accurate analysis, judgment and alarm of common camera failures such as black screen, blurring, out of control PTZ, picture freezing, and video signal interference such as scene change, items left/disappeared, etc. Camera Kits System With 8 Camera,Wireless Nvr Kit,Retail Store Camera System,8 Channel cctv set,NVR Security Camera Kits System Shenzhen Fuvision Electronics Co., Ltd. , https://www.szsolarcamera.com
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Lamp panel
The lamp panel is divided into ordinary infrared lamps (Dingyuan and Guanglei) and array lamps. The array camera is also divided into 1W, 2W and 3W. Therefore, when choosing infrared lamps, if it is an ordinary infrared lamp, try to choose Dingyuan and 3W array lamps. Since the appearance of infrared lamps is generally invisible, some cottage cameras are filled with Guanglei and 1W array cameras are filled with 3W array cameras. Therefore, try to choose a large brand when choosing cameras.
Maximum Aperture
The real value of the maximum aperture is to improve the light intake under low light conditions, so as to achieve the best exposure combination. In general, the ability to visualize the lens is not required for shooting landscapes. In addition, the lens caliber is not required for shooting landscapes except in particularly dark places. However, when the 70-200mm zoom lens is equipped with a 2-fold zoom lens to make the telephoto section become 400mm and AF is used for automatic focusing, it is better to choose a lens with the largest aperture of F2.8. Large aperture is conducive to accurate focusing in dark conditions. When shooting people with a large aperture lens, even in places where the light is weak, the handset can also use natural light to shoot. In addition, the lens with the largest aperture can bring fast shutter speed, so sports photography also needs a large aperture lens.
Another reason for requiring the lens aperture to be large is to be able to visualize the background freely and ensure the quality of visualization. When the aperture of the lens with the maximum aperture of F1.4 is reduced to F2, both the imaging quality and the blurring quality of the background are better than those of the lens with the maximum aperture of F2. Therefore, it is of great value to reduce the aperture of a large aperture lens by one stop. Any photographer should be good at using the lens.
focal length
The first thing to pay attention to when selecting a lens is the focal length of the lens. In fact, focal length is a matter of perspective. Different focal lengths and perspectives are different. In addition, users should be clear about what is the main purpose of buying lenses? Is it for scenery or people. As we all know, it is better to use a wide-angle lens when shooting landscapes, and a telescopic lens when shooting people. Therefore, you should first decide the focal length of the lens you want to buy according to the purpose of photography.
The best focal sections for shooting scenery are 24 mm wide angle focal section and 200 mm telescopic focal section (both are based on 35 mm specifications, the same below). When the wide-angle focus segment of the standard zoom lens evolves from 28mm to 24mm, the viewing angle becomes larger, and the range of scenery that can be stored is greatly expanded. Generally speaking, the maximum aperture of the lens is not required for shooting landscapes. If you are mainly shooting landscapes, a wide angle focal length of 24mm is basically enough when you select a zoom lens. As for the telephoto section, it must be at least 200mm. If the telephoto section is 300mm or 400mm, it is more ideal, and the degree of freedom will be greatly improved. The telephoto focus segment of traditional zoom lens is 300 mm, which is 450 mm for digital SLR. The focal length has been expanded by 1.5 times, which makes it more enjoyable to use. This is the value of digital SLR. The wide-angle focal section of the digital special ultra wide-angle lens produced is generally 12mm, equivalent to 18mm of 35mm, which is nearly 1.5 times larger than the 28mm focal section of 35mm, thus greatly widening the left and right range of the scenic scene.
The best focal length for shooting people is 85mm. In terms of 35mm standard, 85mm focal length is basically used as the standard for shooting characters. The portrait taken by the 85mm focal section is basically close to the picture effect taken by the medium frame camera. It is not only suitable for the distance, but also the face of the person looks very natural. The distance between the camera and the person being photographed can basically be kept at the normal speaking distance. The 85mm focal length can also effectively blur the background and prominent characters. In order to obtain good visualization effect, the lens with the largest aperture should be selected. The 85mm focal length is about 135mm on the digital SLR. Although the sense of distance of the shot is a little weak, it is basically OK, so the focal length of the person lens should be at least about 85mm.
A 100mm macro lens is enough for traditional SLR to shoot flowers. The 100mm macro lens can be used for equal magnification photography, which can make the flowers very large. However, when taking equal magnification photography or near equal magnification photography, due to the depth of the long focus scene, it is easy to shake, so anti shake measures should be considered when taking photos. From this point of view, 50mm macro lens is easier to use on digital SLR.