A rear view camera in a vehicle is like having eyes in the back of your head. Even cars with good rearward vision benefit from one as they are mounted on the outside of the vehicle at the very back. This is a simple guide to help buyers find a system that suits their vehicle and works effectively and reliably.
HARDWIRED VS WIRELESS
Wireless systems seem easier to install however still require power wires to be connected at both ends. All wireless devices are open to interference and most wireless receivers can often even pick up other cameras instead of their own. This is unacceptable for a safety product and defeats its purpose. Hard wired systems are the only recommended systems.
MIRROR IMAGE
Be sure that the camera you are getting is for vehicle rear view and the image is in fact reversed as it would appear in the mirrors . A few of the more high tech lcd monitors allow the image to be flipped around so extra cameras can look forward but usually it is best to use cameras designed for the job . Some so called rear view cameras are actually CCTV cameras and don’t have this important function so the driver can see an image mirrored as in their rear view mirror. Never use a camera without this feature.
VIEW ANGLE
The ideal view angle is about 120 degrees suit trucks and other large vehicles. Wider angles such as 170 degrees that give peephole type view are becoming the norm for cars . Narrower angles like 90 degrees are dangerous as they usually won’t see all the blind spots outside the side mirrors.
INFRA RED NIGHTVISION
It’s best to choose a camera with this feature although the worst object you could hit in a vehicle (kids) should be in bed during the hours of darkness. However, it usually won’t cost much more and supplements the cars reversing lights which are often inadequate . Some of cameras have very good night vision and can see objects in complete darkness in quite some detail . The infra red LEDs ( light emmitting diodes ) automatically turn on when light on a sensor bulit into the camera is to low to see well , the picture will switch to black and white from colour at night .
PICTURE QUALITY
The two most common video image sensors and called CMOS and CCD. CMOS is smaller and cheaper but of poorer picture quality especially at night but are ok for a family vehicle. CCD is best and although the price can be noticeably higher it does produce a much higher quality of image. A new type of sensor that is becoming available is called CMD which is similar to CMOS in quality and costs. The number of TV lines are also a factor, anything under 420 TV lines produce poor images.
WEATHERPROOF CAMERA AND WIRING
As cameras are mounted on the outside of the vehicle they need to be waterproof. An international rating called i.p. rating is the best measure and the higher the number the better. The minimum recommendation is 67 although 68 and 69 are available. Also ensure any exposed wiring is protected with at least insulation tape.
AUTO SWITCHING OR ALWAYS ON
For cars it is recommended to only have the camera image displaying when in reverse , mainly due to current WOF regulations that are vague and outdated . However , heavy vehicles are allowed to display image anytime ,maybe because the don't have much to see in rear view mirror.Most commercial systems allow the driver to turn on system at any time with auto on in reverse . Never use a system that the driver has to activate before reversing. Many systems lack this feature and are unsafe because if the driver is rushing (often when accidents happen) they may not activate the system. This includes monitors mounted on the sun visor that need flipping down. Either the system should activate from the reverse lights or be always on when the vehicle is running.
POWER
All cameras use 12 volt power. Most vehicles have 12 volt power however some use 24 volt systems like trucks and other larger vehicles. Voltage converters are available to reduce the voltage or preferably there are systems that have free voltage 11-32 at the monitor and the cameras are powered from there. These are best as power only needs to come from one source using a fuse and the voltage is regulated from the monitor often the systems can power several cameras that can have a priority order when activated (eg. a rear view camera as 1st priority then two side cameras that activate when indicator comes on). Always use a fuse.
MONITORS
Many of the LCD monitors advertised for vehicles are unsuitable for rear view camera use. Only LCD-TFT type provide a clear picture over the wide range of lighting conditions encountered while driving. Monitor size (measured diagonally) usually ranges from 2.5 to 7 inches. 3.5 inches is the minimum recommended to see hazards and suits most cars. 5 to 7 inches are best for vans ,trucks and buses due to the larger blind spot. Obviously monitors that are mounted behind the drivers head-rest won’t do but let’s examine some of the common types and their pros and cons. Many Japanese imported vehicles have GPS navigation screens and most have an input plug that’s for a rear view camera and provide a cheap effective solution. High end GPS systems also have these inputs. Some stereo systems also feature an LCD screen with inputs, however, these are usually mounted to low and on the wrong angle for the driver to see easily. Most common are panel types usually with a removable bracket so it can be fixed to a flat surface. The best type tested replace or slide over the existing rear view mirror. On some the screen is the full mirror about 6 to 7 inches and on others the LCD is on one side (the side of the driver) and a mirror on the other. This position is the most natural place to look to see back and provides best all round vision of side mirrors, in front, and behind. It is also unobtrusive in the interior, especially from car thieves scanning vehicle interiors for items to steal.
CAMERAS
The cheapest or simplest to mount camera is not always the best. The perfect position is as close to the centre of the rear, possible looking slightly downward giving an overview of the blind spot the vehicle intents to travel. Truck box type were the first seen on the roads featuring an adjustable U bracket and often a sun visor and are still the standard type used on trucks and buses. Bullet type with a small bracket are common and easy to mount but can be knocked or vandalized easily. Number plate types are easy to mount but can move from the slamming of the car boot and some types actually block the lettering of the number plate. flush with the bumper type are robust although they are mounted low collecting heavy road grime and often get sun strike easier from the low view angle (sun can damage the delicate image sensors in the camera). Small wedge shaped cameras designed for under body or under the lip where the number plate lights sit are robust, easy to mount, cost effective, and work. Recently vehicle model specific cameras entered the automobile industry due to the demand for rearward visibility. There are so many models now being made we can’t review all of them here. Our general conclusion on these was that few offer any infra-red night vision and not all mounted at the centre. All cameras should be fitted as close as possible to the centre of the vehicles rear to give even coverage of blind spots.
MAINTENANCE
If you never cleaned your windscreen, eventually your view of the road would deteriorate. The same goes for the camera lens and monitor screen. Road film stirred by vehicle turbulence can obscure the small lens very quickly and whites out the infra-red image at night. Clean regularly to avoid these hazards. Vibration can often cause cameras to move gradually or they may get knocked and even flush mount types often swivel in their hole. Check view angle before moving. Cheaper cameras can get condensation in them and fail rapidly once this happens.
INSTALLATION VS DIY
Many kiwis with basic automotive electrical knowledge could install their own system provided they have followed this guide and purchased a system that suits the vehicle. If that describes you we also have an DIY INSTALL? guide that may help. If it doesn’t or you are too busy, choose a reputable Auto Electrician who can provide a warranty for their work or look on our list of DEALERS or CONTACT us to find one in your area.
Feel free to view our other guides.
