Buying Security Cameras: A Beginner’s Guide

 

Chinavasion likes to give its customers choices, which is why many of our products may come with different versions but with small differences.

Security cameras are no exception and in fact, the many different specifications and functions available quite often confuses the average buyer. That is why we dedicate this article to briefly explaining the most useful parts of a security camera so that you, the customer, can make an informed decision on which type to use.

As this is a guide made for the not-so-technically-inclined, 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.

Image Sensors

 

 

Image sensors are one of the most important part of a security camera as you would be blind without one. The two most common types are CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor), which uses two completely different technologies for capturing images.

You also have the Super HAD CCD and Interline CCD, which are improvements upon the traditional type of CCD, for a total of 4 different image sensors. What’s the difference?

CMOS:

• Uses only 1/5 to 1/10 as much power as CCDs
• Cheap due to low cost of production
• Great for battery-powered cameras

 

CCD:

• Less electronic noise than a CMOS
• Better image quality

 

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

 

Interline CCD:

• High resolution
• Large pixels for high sensitivity
• High frame rates with multiple outputs
• Fast line dump for faster sub-sampling
• Low image lag and smear
• Great for machine vision, microscopy, fluoroscopy, and other applications that demand high imaging performance.

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 soely depend on the image sensor. Look at the other specifications too.

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:

• A poor quality or badly set-up camera.
• A poor quality or poorly focussed lens.
• Poor quality video cables. These can cause distortion of the high frequency analog signals.
• The network bit rate used to transmit the video. If the bit rate is too low then TVL will be reduced.
• Product quality. Poor design of the analog to digital conversion electronics can greatly reduce TVL.

 

 

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.

 

Some of the wireless security camerasavailable at Chinavasion
 

 

Some of the wired security cameras available at Chinavasion

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.

Useful Features

 

 

Waterproof/Weatherproof:

Security cameras have to be sturdy, they have to be resilient. When Mother Nature throws a fit, your security camera should be able to say say “Back off, yo.”

But how do you measure the durability of security cameras? Luckily for you there’s something called the International Protection Rating or the Ingress Protection Rating.

This is a system which can the rate of durability of everything against water and solid objects and is an especially important piece of information to know when you’re dealing with an outdoor security camera system.

To help with that, Chinavasion security cameras all come in a strong heavy-duty aluminum casing to protect against water, stormy weather, falling debris, and even vandalism and often have a IP66 or IP67 rating.

 

Night Vision:

What security camera doesn’t have night vision nowadays? Hey, let’s create a security camera that only works during day, where crimes are less likely to occur! So unless your security camera is indoors and the room is guaranteed to be lit 24/7, you will probably want a security camera with IR (infrared) lights.

Just as shining a spotlight on something makes it easier to see with your eyes, lighting up an area with invisible infrared light greatly improves night vision. The only compromise is color as all of your images will be in black and white. You’ll have to agree though, that’s better than just black.

Motion Detection and Alarm Settings:

How great is it that you can set your security camera to send an email to yourself (or even the police) when it notices something is moving when it shouldn’t be?

Not only that, but our security camera’s software can automatically take a picture or start recording video when it notices something is moving. You can then have it automatically be uploaded to an FTP server.

There are so many uses for motion detection and there’s no other way to describe it except for being an essential part of any security system.

Insert I45/I44 Motion detect picture

PTZ:

PTZ stands for Pan, Tilt, and Zoom, which are functions you can use to move and control your security camera. While it may sound useful for some, it’s probably better to just buy 2 security cameras and here’s why: While the security camera is looking at sector A, you miss the footage on sector B. When you move it to look at sector B, you miss out on everything that happens in sector A.

Also, you probably won’t be there to manually control your security camera 24/7, so what happens then? The best, but more expensive, solution is to buy another security camera so you can keep an eye on everything at any time. Location and placement then becomes the most important factor in ensuring the most effective surveillance, but that is out of the scope of this article.

I might have left out a number of details which our security camera veterans might be picky about, but please remember this is a “Beginner’s Guide”. If there is enough interest, we might publish a part II on security cameras, make sure to keep an eye on the Chinavasion Blog!