Guide to selecting or specifying residential cameras
Choosing the right cameras is the most important part of any surveillance system. Since price is the only thing all customers understand, many customers choose low cost cameras that fail to meet their needs and are left with nothing but a bad taste in their mouth about surveillance. Today we are going to walk you through the specifications of cameras so you can choose a camera that meets your needs.
First decision to be made is home much detail do you desire to see. Are you just trying to see if there is a car in the driveway or not, or are you trying to identify which one of your neighbors are going through your trash. Four characteristics Determine the quality of captured video: TV Lines (aka Resolution), Image Sensor, DVR Resolution, and Frame Rate.
TV Lines (Resolution)
TV Lines, or Resolution is usually specified as TVL. Common resolutions are 420, 480, 540, 550, 600, 650. Resolutions as low as 420, or 480 are great for seeing whether or not there is a car parked in the drive way or out front, but they will fail to give you the detail you need to identify a person in your driveway trying to break into your car. Resolutions like 540, and 550 are more ideal for identifying poeple at various distances or seeing detail, but still are unable to reliably capture enough detail to read a license plate out at the street. 600, and 650 TVL Cameras are the top of the line right now. These cameras capture enough detail to clearly read license plates and identify people at long distances.
Image Sensors are the component in the camera that actually coverts the light into an electrical signal. There are two basic types of image sensors CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor). CCD Devices are a little more expensive because they require more external components in the design and manufacture, but they produce higher quality images with less noise. CMOS sensors on the other hand are mass manufactured low cost because all the comments needed to function are built into the chip itself. This make this the camera cost less, but you also sacrifice quality. Image Sensors are measured in inches. Low cost cheap cameras tend to have 1/4 inch image sensors, while more expensive quality cameras will employ 1/3 inch image sensors.
DVR Resolution and Frame Rate
DVR Resolution is the same as your monitor resolution or the resolution on your flat screen tv. It determines the image size. Resolution can be though of like Mega Pixels in digital cameras. The more Mega Pixels, the bigger the picture and the more quality you can see. The bigger the resolution the better the picture. Low cost DVR’s will have low resolution such as 352 X 240 or CIF, while a quality DVR will record at D1 or 704 X 480. New compression technologies such as H.264 allow higher quality video to be stored on less hard drive space.
Frame Rate is how many frames per second are recorded on the DVR. Frame rates of 15 fps will show video that is very choppy. Frame rates of 30fps will play video in real time showing smooth motions. Hollywood motion pictures are produced at 30fps. Most DVRs can record 30FPS, the catch is, you want to be sure that the DVR can record 30fps per channel. For instance on a 4 channel DVR you would need a DVR that could record at 120 FPS to get full real time recording on all channels.
Indoor / Outdoor
If you decide to mount your cameras outdoors you’ll definitely want to consider the cameras weather proof rating and whether or not it’s vandal Proof.
Weather proof Rating
Outdoor camera ratings will usually be show as IP## such as IP65. Ip is short for Ingress Protection Rating, or in other words: What it will keep out. The first digit is a rating on how well it keeps out solid particles, while the second digit is how well it keeps out liquid particles. For instance an IP51 will have a level 5 solid protection which will resist dust but not be dust proof, and it will have a level 1 on liquid protection which means it will resist dripping water but not wind blown rain. All outdoor cameras should be at least IP65 which means they are completely dust proof and will resist water blowing in a hurricane. Due to the small price difference between outdoor and indoor cameras, many reputable camera companies will use outdoor cameras inside because their dust resistance will increase the cameras life span.
If you intend to place a camera outdoors its important to get a vandal resistant camera. These cameras usually come in dome shapes are are capable of taking a hit from a basketball, rock, or even a direct hit from a baseball bat. Bullet Cameras can also be vandal resistant, but by the nature of their design and profile are more susceptible to physical attack.
Day / Night
If you plan on using a camera in the dark you definitely want to consider its night vision specifications. Most modern security cameras come standard with night vision features today. Residential cameras utilize Infra Red Light Emitting Diodes or IR LEDS for short, to illuminate the area while the camera switches into black and white mode to pick up the LED Light. This IR Light is invisible to the naked eye but allows the camera to see in total darkness. The important factor to consider when choosing a camera is how many IR LEDs are built into the camera. A single led keychain doesn’t throw as much light (or lumens) as a Mag Light flash light for example. The more LEDS the brighter the flashlight and the better / further your going to see in the dark. Low cost chinese cameras will come with 14 or fewer LEDS. This will give you a decent picture a couple feet out, but beyond that you’ll be in darkness. For a great image 30′ to 60′ out you want at least 24 LEDS. If you get up around 42 LEDs You can see in total darkness over 90′. Many times the image is better at night when the light is controlled then during the day with the blaring sun.
Viewing Area / Viewing Angle
When selecting a camera its very important to consider how far it will be away from the object your wanting to see and what angle of view you desire. These characteristics are determined by the camera lens. For example if you were to mount a camera a few feet away from your front door you would want a camera with 3.6mm lens to get a perfect shot of the person standing at your door. However if you were going to mount cameras on your second story eve, then you would want a vari-focal 2.8-12mm lens that would allow the installer to set the perfect viewing angle and focus so that you will see exactly what you want, and so it will be in focus. Low cost cameras typically come with a 4.6mm lens and that has a fixed focus. This one size fits all lens which doesn’t perform well when hung under a two story eve or when stuck up close to the object your viewing. When it comes to lens size, the bigger the lens the more the zoom. The smaller the lens the wider the angle.
Since cameras are designed to work well in all light conditions they have to be sensitive to light. However, the sun is so bright that it can wreck havoc and even render a camera useless for several hours a day. This problem has been solved and many high end cameras have something called a dual window structure which prevents the reflection of the sun from having the blinding effect on the the cameras. This feature is not available in low cost cameras and is one that should definitely be considered when putting a camera in an area dominated by the sun.
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