I installed a security camera system a few years ago and that’s when and how I got my education in the subject.  I’ll share what I learned with you but be warned, if this is not an interesting topic for you, read something you’ll enjoy, like, “Robert’s Rules of Order”.

I installed a complete “home” DVR system (digital video recorder) that came with several cameras, the DVR, software, wires and everything I would need.  I can watch my cameras on my TV, laptop, phone and at home or anywhere in the world.  It stores video for about three weeks and it sends photographs to me by email when certain alarm events occur.  I’m sure there are commercial systems and CIA systems that exist but my system cost less than $1,000 and that is the level of product I will discuss here.

While my system is less than five years old, there are two newer generations of the system on the market today.  The first generation after mine uses 960h picture quality and the current standard uses 1080p picture quality.  To put it in context, my system provides the video quality similar to the very first camera phones, you know, those old flip phones or about 1/4 Megapixel. 960h is about 50% better.  1080p is roughly 2.1 Megapixel which is about 10 times or 1,000% better than my system.  That’s still not very high resolution considering what your iPhone or Android can shoot.  But, recording and storing 8 or 16 cameras, 24/7 for three weeks at 6 or 10 Megapixels would require a MASSIVE hard drive.   The systems that support Megapixel cameras often use the term “Network Video Recorder” or NVR to describe their high end DVR.  
(see: http://www.security-camera-warehouse.com/knowledge-base/comparing-420-480-600-700-tv-lines-php/)

There are other options.  Some people use Game Cameras, cameras that are designed to be used in the woods by hunters to record deer and hogs as they eat the food the hunter puts out to attract them.  A very cheap game camera produces 2 Megapixels and a very good one produces 14 Megapixels.  But, there are two other features that are important on game cameras.  Many of them do not use invisible infra-red flashes and most of them do not shoot the first picture very quickly.  In a security setting, it is possible that your “game” will be out of the frame before your game camera gets off the first shot.  And, if it shoots a visible flash, your “prey” may come back and modify your camera for you.  The 14 Megapixel camera I mentioned shoots its first photo in .2 seconds which is very fast for the category and it shoots a “black” infra-red flash and costs under $200.  It is manufactured by Bushnell.  The problem is that it is not networkable.  About once a week you need to go out to the camera and remove the SD memory card and review over 1,000 photos.  And, by the time you buy eight of them you will have spent more than I did on my system and you will be very busy reviewing photos.

Another option is the Net Cam.  There are several versions of these by various manufacturers with various software features.  Google owns a company, “Nest” that makes such a camera and it produces impressive daytime and night time photos with sound and it records video through your WIFI up to the web. That’s a cool safety feature because once the video is on the web, a thief can steal the camera but not the video.  But, they only store the video for a week so if your vacations are longer than a week, you may return to an empty house and no video.  Other companies sell similar equipment and services but probably not higher quality video.  One other detail, these cameras are not weather proof so you will need some kind of weatherproof housing.  You can buy these cameras at Best Buy, Wal-Mart and Amazon for about $100 but the web recording service costs about $10/month.  Some of the cameras in this category allow you to record on your desktop hard drive at no cost.

We need to discuss Infra-Red technology (IR).  These cameras do not use IR heat technology, which often requires cryonics or an ultra cold camera and costs millions of dollars.  These IR cameras have LEDs that put out light in the 840 or 960 nanometer (nm) range.  The human eye can only see to about 700nm.  These LEDs produce a spectrum of light and usually the 840nm range reaches into the 700nm range so the LEDs appear to glow orange, similar to a cigarette and are thus visible.  The point of IR is to be invisible so it is important to be certain you are getting cameras in the 960nm range.  I’ve learned that if the box is not marked 960nm or “Black Infra-Red” or “Invisible Infra-Red”, it’s not invisible.  Don’t buy it.

IR is not the answer to seeing in the dark.  IR is just a LED flashlight that the camera is designed to see and the eye can’t.  My experience is that the practical useful distance range of the LEDs is about half what they are marketed to be.  Most are advertised to be good up to 60’ and some up to 90’.  Figure they are good for half of that and even then, often the fringe around the edge of the picture will be darker than the middle.

An alternative to IR is Low Lux.  Lux is a unit of measure of illumination.  As a practical matter, don’t buy a camera that is rated less than .0001 Lux.  These cameras are designed differently than the IR cameras and most of them are sold without the lens.  This gives you the opportunity to buy a zoom lens or wide angle lens or just a lens that is best for your application.  These are referred to as “box cameras” and they are not weather proof, you will need a weatherproof enclosure to use them outside.  Unless you own a bank, you probably will be using these outside.

There are system features that you need to understand:

Motion Detection
Motion detection in a camera is done by comparing the previous video frame with the current one and if they are different, it triggers your motion alarm.  This means, if the wind blows branches or leaves or the neighbor’s garbage or the sun comes out from behind a cloud, your camera will have detected motion.  Even a bird flying in or across the field of view will trigger the motion detection.  Most systems have a system of blocks that you can select on your screen so that you can turn off motion on parts of your screen and not on others.  As a practical matter, this type of motion detection is likely only useful indoors in a controlled environment.

NO and NC Alarm Interface
This is a connection option to your DVR that will accept the output of external devices, such as door switches, magnetic switches, PIR movement detectors, etc.  Most systems do not have this option but it is very handy if you are serious about a multifaceted security system.  (NO means Normally Open and NC means Normally Closed.  This is common technology in alarm systems.)

These devices are ususally PIR motion detection, laser trip wire or metal detection for vehicle detection.  When triggered, these devices transmit to their base station which then triggers the DVR if it is wired into it.  The DVR senses the alarm event and takes pictures from predetermined cameras and emails the photos to the administrator.

Facial Recognition
Some systems claim to be able to differentiate between a human face and a dog or leaves.  I have no experience with this option except that most of the time the person I am watching in a video of interest does not show their face except for fleeting moments.

Remote Access
With the exception of the NestCam, you will need to know how to configure your router if you want access to your cameras remotely.  If you have set up a router before and are just “proficient”, you likely will be able to do this but, it will take the better part of a Saturday.

Covert Cameras
You can buy cameras that look just like a smoke detector or PIR movement detector or digital clock that tie into the DVR systems or work stand alone.  My experience though, is that you want to see the crooks before they get into your house and you have your home alarm system set to go off as they enter.  To me it is pointless to be able to see a crook rifle through your wife’s jewelry. And your wife may not be too happy with you when she finds out what else you have captured on that camera.  Use these cameras for monitoring infants or baby sitters or your most vulnerable entry point, not your hallway or bedroom.

My experience is that you need a mixture of technology.  You need the highest megapixel cameras you can afford but the video probably will still not identify who the thief is or their license plate.  You will probably want a game camera for the identity and the video to learn what they did.  You will want IR cameras in dark places close to your house and low lux cameras for looking out into the street or cul-de-sac.

Think twice before you put in a camera system. The night is alive with activity and you may sleep better not knowing what is going on in the dark outside your house at night.  And, a camera system absolutely does not replace an intrusion alarm.