Accessory backup video systems for cars are widely available with several electronics manufacturers competing in the market. While the primary mission of these minicams is simply to provide a view to the rear while you're parking or backing up, they also offer a safety advantage because they can help you to see a child, pet, or hazard.

Our previous tests of a few aftermarket models found that performance generally tracked with price—another case of "you get what you pay for." That said, even the worst performers are better than a beeper-type parking aid at seeing objects or people behind the vehicle.

Why you need to eliminate the blind zone

Every year, thousands of children are hurt or killed because a driver backing up didn't see them. The safety advocacy group Kids and cars calculates that two children are killed and 48 are seriously injured this way every week in the United States. For the most part, back-over incidents take place in residential driveways or parking lots and about three-quarters of the time it is a parent or close relative who's behind the wheel.

The main reason that back-over accidents are so frequent is that every vehicle has a rear blind zone—the area you can't see from the driver's seat. And that zone to the rear is bigger than you might think, ranging from about 25 feet for a minivan to 50 feet for some pickup trucks--plenty of space for an unwary child to be in harm's way. (Read: The danger of blind spots.)

Many new cars have proximity sensors that beep with increasing frequency when you back toward solid objects. The sensor systems might work well as parking aids but they aren't informative enough to tip you to the presence of someone, particularly a small child.

Other vehicles have backup cameras incorporated into their ($2,000 to $3,000) navigation system and some appear in the rear-view mirror. When you shift into reverse, the screen shows a wide-angle or fish-eye view to the rear. Camera systems are much better at revealing objects you could not otherwise see through the windows and mirrors.

Aftermarket sensor and camera systems allow any vehicle to be retrofitted with some sort of warning device.

How they work

Aftermarket backup cameras have adopted various designs. A small video camera is sometimes built into a license-plate holder or mounted in a trailer-hitch receiver or on a car's bumper.

Systems typically use a video screen built into a replacement rearview mirror, an accessory add-on monitor for the existing mirror, or a flat screen that mounts to the inside of the sun visor. Some systems are wireless, but most require wiring that snakes through the vehicle from the camera to the system's video display and on to the car's electric power system. Complicated, hard-wired systems are best installed by a professional.

Besides scouting for children, a camera mounted near, or in, the rear bumper can come in handy if you're trying to mate up your vehicle with a trailer. With a camera showing you where the hitch actually is, there's less need for a helper to call out directions to you.

None of the systems we've tested is ideal. The parking-sensor systems aren't discriminating enough to act as a truly useful safety device. Those that use a display built into an inside mirror seem promising, because the mirror is a natural place to look when you're backing up. But their display is often small, or indistinct, and the add-on mirror assemblies can be quite bulky. The viewing area from some cameras is quite narrow, and some cameras are prone to fogging up too easily.

Still, any camera system is more informative than a mere proximity sensor.

How to choose

Aftermarket companies offer three types of backup systems: rearview cameras, sensor systems, and wide-angle lenses. Use to decide which best suits your needs. For wired camera and sensor systems, we recommend professional installation.

No matter what type of system you choose, consider the following when deciding on a specific model:

Know how the device mounts on your vehicle

Camera and sensor systems that are mounted on the vehicle's bumper or bodywork might require drilling. They might not be the best choice if you lease your vehicle.

If you have a trailer hitch, you can consider a model that mounts in the hitch receiver. But you would have to remove the system to use your trailer.

Other camera and sensor models mount on the license-plate frame. But some states prohibit frames because they can obscure the plate.

Within types, features vary

That is especially true with the sensor models we tested. The ultrasonic systems were generally the most sensitive, but their performance was adversely affected by rain, snow, or other inclement weather.

The microwave-based sensor systems we tested were not affected by weather but are less sensitive as a group. They also don't warn the driver unless the vehicle or object behind it is moving.

The display quality of the camera-based models is very good, although it doesn't match that of the larger screens on some carmakers' integrated navigation systems. All of the system displays turn on when the vehicle shifts into reverse.

All the systems we tested are potentially useful. They're a good complement to looking around the vehicle before entering, and checking the rear window and rearview mirror just before and while moving in reverse.

Haloview MC7101 7" digital wireless backup camera system with built-in DVR

The Haloview wireless backup camera has 120°wide viewing angle. It also has a great senson which provide effective pixels of 756 x 504 pixels, it is enough for recrease awareness for safe driving. 

It has 4 high power IR lights 4 high power LED lights provide 32 feet of night vision for cameras. The minimum illumination for the camera is 0Lux. And power supply for the camera is ranged from DC 10-32V.  

Its IP69K completely waterproof rating make it works well under damp environment. The camera has an adustable heavy duty metal sunshade, protecting camera from glare and pebbles. With a 10G vibration rating, this 

camera is strong, reliable and shock resistant.   

Another featuring of the camera is SMART IRCUT function. The 4 high power infra-red lights combined with 850 LED lights offers better night-vision image. The infra-red sensor in the camera opens automatically at low light. Haloview MC7101 is tough enough offering you reassurance and safety.