How does a speed camera work?

On doing some research & calculations it has been found both correspond, that at 80.45 KM/h (legal speed of 50 m.p.h.) a motorist needs 3.3 seconds to stop to 0 m.p.h. safely & a distance of 45M. Therefore it is unsafe for a driver at this legal speed to attempt to stop a vehicle within 45M of a traffic light. (for this reason isn't a camera pointing the wrong way.) Therefore if a police camera cannot be shown to offer this 3.3 seconds from green to red inclusive with photographic evidence that the vehicle had crossed the marked line outside the 3.3 seconds then surely it is fraud, unsafe practice & illegal operations? (which I don't doubt is the truth of the matter) A 'cop friend' tells me on getting a red light offence it is within rights to ask for the cameras cabrillation for that day. Therefore does anyone know what information this cabrillation shows & would it show traffic sequence timing? For that reason how does a speed camera actually show that you have jumped a red light?

Fantastic answers so far. My point is one of safety. Whereby considering the facts of physics it is unsafe to stop at a red light if within 45M. It is v.simple to say the Law is yes or no ignoring the factors of safety. Surely if safety was the only concern there would be no red light cameras and a greater time delay on the other directions. Or in Asia have count down timers illustrating how long Amber is. In Thailand people have 60 secs for amber.

You are supposed to slow down approaching traffic light so you can stop safely if required.

The amber light gives sufficient time for a vehicle being driven at the correct speed to pull up.

The way a traffic light camera works is that a motion detector is activated as the light turns red. Any vehicle passing will have a photo taken.

I have heard of people getting off with a red light offence when the road was very wet, but I would think that conditions would have to be extreme. I have also heard of people getting off when there was an HGV close behind them. However I have also heard of people being convicted of the offense when they had pulled through to allow a blue light through.

Basically if you went through a light at red you were not driving properly and can't really complain if you get done.

I imagine they are timed to snap pictures as the light turns red. I have seen some of these with a green to red light transition time of around 1 second, and it is dangerous, clearly it was designed to unfairly catch people running red lights. I did not know we had the right to know the light's calibration, I will keep that in mind. I would hope that it gives you information on the timing of the lights.

Traffic signals have 3 seconds leaving amber.
Most Red Light cameras are set to flash after 2 seconds of red, if it detects a vehicle crossing the inductive loops beyond the Stop line.

The amber light tells you to slow down before it turns to red. it gives you 3 seconds to slow.