To be honest, it doesn't matter. They will only take your photo if you are going over the speed limit. To do this they use detector loops which are in the road about15 - 20 feet in front of the camera (they are the black thin rectangles). The white stripes just confirm your speed on the photo. So they only need to be able to 'see' 20 odd feet. The only way to avoid getting your photo took (assuming you are speeding) is to go past at 162+ mph. The camera can't react quick enough then!