There's no denying the allure of a gadget that can outwit the unblinking eye of the photo-enforcement camera. Whether it's a red light or speed camera or a roving photo radar (speed) van, this technology is used in 22 states and continues to spread.
Red light cameras monitor more than red lights: many also watch for a right turn on red where the vehicle fails to halt. Same for left turns on red, and they're frequently used to generate speeding tickets as well.
Products claiming to defeat cameras fall into three classes: passive, active and radar detectors. Passive products include license plate covers. Made of clear polycarbonate, they have a thin layer of prismatic material positioned over the alphanumeric characters. Viewed at a zero-degree angle—from directly behind—the plate can be read. But as one moves to the side and the angle becomes greater, one or more of the numbers will be obscured. At least that's what the manufacturers promise.
There's also a clear spray called PhotoBlocker that promises to make the plate so reflective it overexposes the photo. A competing spray, Photo Stopper, is sold by On Track Manufacturing.
Active devices include a solenoid-activated plate-flipper that flattens the plate to hide it. A few adapt electrochoic Smart Glass technology that makes clear glass cloudy by applying an electrical charge. Another blasts the camera with a strobe flash, claiming to blind it.
Most of the passive products capitalize on the fact that the roadside-mounted camera operates at an angle from the target vehicle's path, called the cosine. Photo radar commonly is aimed at an angle of 20 to 22 degrees across the road. Regardless of the type of photo enforcement, to make the offense prosecutable the enforcers must identify the license plate. In some states a photo of the driver is also required. No plate means no vehicle ID and no ticket.
Some radar detectors can also protect against cameras. A GPS-enabled model stores camera coordinates in an onboard database and warns when a camera is approached.
Escort was the first with a GPS-enabled detector, but Radenso and Uniden have made inroads. Each offers lower-priced GPS models with similar features and performance.
Without the ticket-reimbursement program and with lower performance and fewer features is the Uniden DFR7.
To test the plate covers and PhotoBlocker spray we borrowed a $40,000 Multanova photo radar unit. Then we constructed a red light camera system that replicates those of ATS and Redflex, the firms controlling about 90 percent of the domestic automated enforcement market. Learn more about how we tested the plate covers and PhotoBlocker.
We tested the radar detectors against a Redflex red light camera radar in nearby Scottsdale, Arizona. Learn more about how we tested the radar detectors.