BUYING SECURITY CAMERAS: A BEGINNER’S GUIDE
◌ Security cameras are no exception and in fact, the many different specifications and functions available quite often confuses the average buyer. As this is a guide made for the not-so-technicallyinclined, we won’t bore you with the details about how the image sensors absorb light and transfer them into electronic signals or how TV lines are related to bandwidth. Instead, we bring you the meat, the details, and important facts you can use.
1. Image Sensors CMOS ◦ Uses only 1/5 to 1/10 as much power as CCDs
◦Interline CCD
◦ Cheap due to low cost of production
◦High resolution
◦ Great for battery-powered wifi cameras
◦Large pixels for high sensitivity ◦High frame rates with multiple outputs
CCD
◦Fast line dump for faster sub-sampling
◦ Less electronic noise than a CMOS
◦Low image lag and smear
◦ Better image quality
◦Great for machine vision, microscopy, fluoroscopy, and other applications that demand high imaging performance.
Super HAD CCD ◦ Twice as sensitive as traditional type of CCD ◦ Has a 6 db better smear rejection ratio than the formal traditional type of CCD
◌ In the end, which is best? You might quickly vote for the Interline CCD, and you might be right, but recent advances in technology have minimized any quality differences between CMOS and CCD, so to a beginner I would say: It’s pretty much the same since image quality does not solely depend on the image sensor. Look at the other specifications too.
2. TV Lines ◦ “TV Lines” refer to the horizontal resolution measured in relation with the picture’s height. That is, for a standard 4:3 aspect ratio, your 720 pixels accross the screen divided by 4/3 would give a max of 540 TV lines in theory. Of course, it depends on the lens, the ccd, the camera output direct to a monitor, etc. The important thing to know is: The more the better. ◦ Causes for low TVL : 1.A poor quality or badly set-up camera. 2.A poor quality or poorly focussed lens. 3.Poor quality video cables. These can cause distortion of the high frequency analog signals. 4.The network bit rate used to transmit the video. If the bit rate is too low then TVL will be reduced. 5.Product quality. Poor design of the analog to digital conversion electronics can greatly reduce TVL.
3. Wired/Wireless ◌ There are many reasons to choose wired security cameras and many reasons to choose wireless security cameras. When making that decision, there are plenty of factors to consider: the size of your home or property, the placement of the cameras, the cost, even weather and network interference. Wireless security cameras with long signals are very convenient because you can place them in many different, hard-to-reach spots, without worrying about wires or cords. The signals can also go up to 1000 feet, which means you can have your wireless security cameras in areas that didn’t have the proper outlets for regular wired security cameras. Wired security cameras, on the other hand, tend to be more cost effective. You never have to worry about dropping the signal or worry about obstructing or otherwise affecting the wired security cameras signal. One is obviously not inferior to the other, there is only one better for your needs.
4. Useful Features ◦ Waterproof/Weatherproof ◦ Night Vision ◦ Motion Detection and Alarm Settings ◦ Pan, Tilt, and Zoom
Thank You
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