With regards to the current poliscan laser mobile cameras, do they get your speed 1st futher down the road & then wait for you to drive closer before taking your photo or is your speed taken around the same time (well slightly before) when the photo was taken.
Looking at some of my very old speeding fines, the photo seem to be taken pretty close to the actual camera, rough guess seem to be ~10m or less.
Those fixed laser cameras in the fixed box on the freeway gives the most warning when I'm driving towards them, the one near south tce exit everytime I come back from Curtin heading towards city direction would give me some 10 - 15 seconds of warning.
While normally the detection range appears to be ~100m - 120m which is about 4 or so seconds.