What is the field of view of a reversing camera, and why is it important?
The field of view is what can be seen behind the car, SUV, truck or campervan. Some of this can be seen by using the rear view mirror. What can’t be seen is in the vehicle’s blind zone, or blind spot, and you should aim to cover most of this with a backup camera.
If a camera has a field of view of 60 degrees, it means that the driver has a view angle of 30 degrees on either side of the camera which is on the vehicle’s center line. If it has a field of view of 90 degrees, then 45 degrees is visible on either side of the vehicle’s center line. Therefore, having a larger field, or angle of view, means there is a larger area visible behind the vehicle. However, anything too large can give a distorted, or ‘fish eye’ view. More about that later.
How does this work?
The view angle of a backup camera is determined by the lens and the sensor. When a camera lens offers a wide angle of view it needs a sensor large enough to support it to ensure the picture is of good clarity. If the sensor is ¼ inch across, then it generally supports an angle of 60 to 90 degrees. If the sensor is 1/3 inch across, then it should support an angle of up to 120 degrees.
Angles of View
Generally, neither the smallest or the largest angles of view work well. The smallest view angle generally available is 60 degrees. However, because it is so narrow, being just 30 degrees on either side of the center of the vehicle where the camera is installed, it really only replaces the view from the existing rear view mirror. This could be useful for vehicles where the rear view mirror can’t be used easily or where the rear window is small or partially blocked, but this angle of view doesn’t totally cover the vehicle’s blind spots. Therefore, as the purpose of a backup camera is to show what’s behind and within the vehicle’s blind zone, unless you have a really small car, it is recommended that you buy a reverse camera with a wider angle of view.
The next camera angle of view available is 90 degrees. This is still a narrow angle of view, covering only 45 degrees on either side of the center of the back of the vehicle. Although it will cover some of the blind zone and adjacent area, such as other vehicles and pedestrians in parking lots, drivers will be forced to check both monitor and mirrors to ensure they see anyone or anything approaching their blind spots. Indeed, most safety articles I have read state that drivers should check all mirrors before reversing. That given, although a 90 degree angle could be a good choice for some, most drivers will find a larger angle of view more reliable, easier and safer to use.
A camera with a 120 degree angle of view should be a good choice as it will cover the vehicle’s blind zones and still provide a clear picture. Having a coverage of 60 degrees on either side of the vehicle’s center line means not only the blind spots are covered, but anyone approaching them will also be seen in advance.
A number of systems offer 115, 130 160 degree angles of view. The largest angle of view is 210 degrees. Having over 100 degrees on either side may sound great. However, humans process 180 degrees naturally and so 210 degrees is difficult for us to see clearly. The monitor screen will not be able to show the 180 degrees that are useful to the human driver clearly, instead distorting the whole image, giving it a ‘fish eye’ view. Whilst the image will be visible, its clarity will be diminished. Distances and closing rates will be difficult to judge and it is believed that this wide an angle may actually cause accidents.
Before buying an aftermarket backup camera, you will need to check its field or angle of view. The smallest angle of view that is recommended is 90 degrees, but if your budget and monitor allows, the best backup cameras for most vehicles have a view angle of around 120 degrees. This should allow a wide field of view whilst still giving a clear picture. Of course, all reverse cameras should be used together with rear view and side mirrors, where possible. When used together, this should ensure you can backup safely.