The Elusive License Plate Camera
I am a firm believer in the power of security cameras. Unfortunately, they have a significant limitation: you can't always tell who it is on the video. Don't get me wrong, a good closeup image of someone's face can go along way to tracking that person down, but it is not fool proof. The best way to identify that perpetrator is to have a clear identifier. And unless they hold their driver's license up to you camera, the best way to identify a perpetrator is by their license plate number; however, actually capturing a clear, legible license plate on a moving vehicle in a variety of lighting conditions is elusive. Read on to discover what to look for when considering this type of camera.
So how do you choose a license plate camera? Start by looking a cameras specifically designed to capture license plates. This may sound like common sense, but I have seen many communities attempt to use general use cameras to varying success (or lack of success). Cameras specifically designed to capture license plates are really not good for anything else. Inversely, cameras designed for general video will not give you good quality when capturing license plates. Even expensive general use cameras will struggle giving you a legible image of a license plate. Especially when fighting head lights, tail lights, and motion blur from a moving vehicle.
Now that you are looking at license plate cameras you need to consider the following factors.
Resolution – This is usually measured in “lines” with the higher being better. Anything over 520 should be adequate.
Angle – Try to locate the camera in a position to look directly at the rear of the vehicle. This is sometimes best accomplished by using the existing turns or narrow spots in the road. I do not recommend having a camera angle larger than 15 degrees between the camera and the license plate.
Distance – The cameras should be framed in as close as possible. Most cameras will not capture license plates across two lanes of traffic. You need to make sure that the camera will zoom in close enough that the image is about the width of a standard vehicle. The power of the zoom is often measured in millimeters. Here is a rough estimate of how far away the camera can be located based on the zoom:
5ft-10ft 5mm-10mm 10ft-20ft 10mm-20mm 20ft-30ft 20mm-30mm 30ft-40ft 30mm-50mm 40ft-50ft
Infrared – Most license cameras will have infrared LEDs to illuminate the plate. The camera actually tries to use the infrared exclusively and ignores ambient lighting. In this way headlights and taillight do not “wash out” the image and the camera can capture images in zero light conditions.
Voltage – While many cameras will accept 12VDC or 24VAC, I strongly suggest you stay with 24VAC. A good license plate camera needs the extra power for the internal chipset and also to power the LEDs. If you are in a cold weather environment, the extra power can also be used to power an internal camera heater.
Example of how a general use camera adjusts for oncoming headlights, obscuring the license plate. Example of a true license plate camera dimming the headlights and adding infrared to clearly see the plate.
The final factor has nothing to do with the camera at all. Unless you have someone sitting in front of a monitor with a pen and paper 24 hours a day, you are likely to be recording the video onto a Digital Video Recorder (DVR). All DVRs compress the video that is recorded. Older or cheap model DVRs may compress the video so much as to distort the final image. Frankly, there is no real solution to this other than purchasing a better DVR. The good news is that a quality, eight channel DVR can usually be purchased for less than $500.
There is nothing more helpful to the police than a clean picture of the perpetrator's license plate coupled with a reasonably descriptive face shot. While a legible license plate shot can be elusive, follow the above items closely and the next time that unfortunate event happens on your property-you will be prepared.
About the Author:
Key C. Powell, owner of Key Locksmith Services, has over 25 years experience and understands the unique needs of businesses, homes, and condominiums in Collier County. Key's dedication to customer satisfaction and staying on the cutting edge of current technology has made Key Locksmith Services the premier locksmith in Naples and the first choice of homeowners, Realtors, property managers, and business owners.
Contact Key at:
1029 Airport Road North #7
Naples, Fl 34108
“The KEY to Your Security and Peace of Mind.”