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Security / Surveillance Cameras

Posted by Yoel on

How to choose a surveillance video camera?

While choosing a surveillance videocamera, you'll see the outlook and technical characteristics, such as: "Color, CCD, 1\3", Sony Hyper HAD II, 540 TVL, f=3,6, IP 67, IR 30m, OSD" and something like that. If you are a newbie, you can be kind of confused. However, don't be afraid. In reality, it's much easier than choosing a laptop.

There is a group of basic FAQs, the answers on which will help you easily and intuitively choose the best surveillance camera for you.

Color or Black&White (Color or B\W?)

Color cameras are good in everything. Modern cameras are 80% color. The information about the color is sometimes crucial, especially when the picture is somehow blurred. What was the color of the car? Clothes of what color did the thief wear? Color cameras work excellently if the lightening is ok. When the lightening falls down during twilight or at night, the color picture is very bad and noisy. Many cameras have the DAY/NIGHT mode - in the night mode they become B\W (some of them also switch on the photodiode lightening). The result is obvious - for places with constant normal lightening (for example, for a shop) it's better to choose a color camera. For places with inconstant lightening, (for instance, a courtyard with the parking) variants are possible, but if the camera is color, the DAY\NIGHT mode is obligatory.

B\W cameras, except their drawback, have the whole series of serious advantages. The picture of a B\W camera is more visually precise than the same of a color camera. The sensitiveness of B\W cameras is considerably higher than of color cameras. I.d.,surveillance of the parking space with the help of such camera is possible even at night, without any special lightening - the 25Wt light bulb or one lit window looking at it is enough. The video stream recorded by a video register of a B\W camera is significantly lower, i.e. less hard drive space is used. The price of B\W cameras is slightly lower than of color cameras. The result is obvious: for 24-hour surveillance of the adjusting territory, the sensitive B\W camera is not a bad choice.

External or internal?

The answer may be not so obvious as it seems. For internal spaces, the result is clear and for the nearby territory, it's worth looking for the option of surveillance through the window inside the space. And only if it's completely impossible you should consider the option to install external surveillance cameras. Installation of external cameras will require considering of climatic factors - the hermetic box, the place of installation, and storm protections. And this is more difficult and more expensive. If you neglect this factor, the storm may destroy not only your external camera but the whole video surveillance system. And it's not a rarity.

The camera's construction.

Video surveillance cameras can be module, box mini, cylindrical mini, mini in external hermetic cases, with lightening or without lightening, ceiling cupola, box for changeable focus.

Module cameras are miniature and they are aimed for installing into boxes and building in different objects. It's very good for house surveillance, when the camera doesn't make the interior more beautiful.

Box mini cameras are invisible and they also can be disguised. It's easy to choose lenses with needed focus distance and even to install the lens with the variable focus on them.

Cylindrical mini cameras have the same advantages. When they are installed, they are quite pleasant to look at and they don't spoil the interior. They are more expensive. Some of them are hermetic and work well even on the open air below the tent.

Mini cameras in hermetic boxes with/without lightening are used for external surveillance and surveillance in unheated spaces. Cameras with lightening consume much energy from the source, it should be taken into account while installing the cable.

Ceiling spherical cupola internal cameras. They are made for office false ceilings. They contain a mini module camera inside.

Ceiling cameras in anti-vandal cupola hermetic boxes. They are made for external surveillance under tents, or canopies.

Box cameras for changeable lens. Having the same sizes of matrixes and bigger lenses and the solid electronics, they give a more precise picture, have the control set up and maintenance of the lens' auto diaphragm. Changeable and varifocal long-focal lenses allow you to precisely tune up even a far-off placed camera on the object under surveillance and the automatic diaphragm helps to control even the great difference of lightening (from a sunny day to a moonless night).

For external surveillance, box cameras are installed into hermetic boxes (sometimes with heating, ventilation and infrared lightning).

Matrixes of videocameras. CCD or CMOS, 1\3" or 1\4", SONY, LG, SHARP. What does it mean? What to choose?

CCD or CMOS

CCD is the charge coupling matrix. It is the traditional technology, reliable for guard video surveillance. CCD cameras are a little bit more expensive than CMOS cameras but they are worth of it.

The CMOS matrix is a cheaper technology. You know it well if you've ever seen dull pictures of WEB cameras. This technology is quickly developed thanks to smartphones and other gadgets. Smart electronics can get out of these matrixes even things they don't see. It's called interpolation. Don't take such cameras for responsible usages in conditions of bad lightning. Even if a manufacturer seduces you with sky-risen features for cents. Don't believe them.

1\3" or 1\4" inches.

This is the physical diagonal size of a matrix. Here, the more the better. It's impossible to cheat on the nature. 1\4" cameras are cheaper. With the same focal distance of the lens, cameras with 1\3" will have smaller sight angle. Smaller matrixes of 1\4" sound louder upon the heating.

SONY, LG, SHARP, Noname - there are not so many manufacturers of matrixes in the world. Until now, Sony has been a step ahead other CCD matrixes' manufacturers. Cameras with these matrixes are slightly better and on 20% more expensive than other manufacturers. SHARP matrixes are also good. If the matrix made by an unknown manufacturer (Noname), you should always look at the picture of such camera in twilight and compare it with the well-known manufacturer.

420TVL, 540TVL, 600TVL, 700TVL - they all are resolutions of the videocamera's matrix in television lines. The more they are, the more precise the picture is and the more expensive the camera is. 420TVL resolution is now thought to be a standard one. Here you honestly pay your money for it. High-definition cameras form the more precise picture, which you even may not see - the monitor won't show it and the video register won't record it (if the resolution below D1 is used). If your monitor, register and budget allow it, buy the camera of a higher definition. You'll have the chance to recognize a not well-known face in the cadre or to see the license plate. It's problematic with the standard resolution.

When you're buying a mini camera with 600-700 TVL for a suspiciously low price, you risk to become a victim of a double fraud. Even if the matrix does provide such precision, the tiny cheap lens cannot provide it. The matrix can also not provide that and the picture is formed via interpolation - making up a non-existing pixels. Buying an HD camera, always compare its picture with the picture of the standard definition camera.

The typical example of the fraud: Color, Cmos, 1\3", f=3,6, 700 TVL just for $20 (on the box or in the booklet you can see the shy phrase written in the smallest font somewhere in the corner lens 420TVL). Here you see the cheap camera with the cheap matrix and lens, forming the picture through interpolation for the dishonest marketing.

f=3,6

f=2,8\3,6\6\8\12mm

f=3,6-8mm

They are examples of focal distances of videocameras' lenses. The first line is the lens with the standard focal distance of 3,6mm, which, with 1\3" matrix, gives the sight angle close to the human eye. The second line gives the list of lenses' focal distances with which delivery of this camera is possible. The third line points out that the camera has the lens with the manually changeable focal distance from 3,6 up to 8 mm. Here you can draw the direct parallel with the photo camera having 3X Zoom. The long-focal lens "closes up" the image, the wide-angle "distances" it. You can use a simplified criteria for mini cameras with the standard resolution - the camera will give the image with the adequate resolution on the distance in meters close to the lens' focal distance in mm.

IP 67, IR 30m - this line says that the videocamera is hermetic and made for outdoor usage (IP 67) and also equipped with the infrared lightning for the night time on the distance of up to 30 meters (IR 30m).

OSD - this line says that the videocamera's modes can be intuitively tuned up with the help of the screen menu. The special technological cable is often needed for that, but sometimes the camera or the cable contains the joystick. You have the menu of such type in your home TV set.

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