Speed Camera? How close?

Question

I just went past a speed camera doing about 68 in a 60 zone not noticing and when I saw the speed camera I quickly slowed down to 60.

How close do you have to be for it to catch you? I was about 20 metres away, maybe a little more, and I was around a slight bend.

I have been told you get caught if you are within 10 metres of it.

Answer 1

It detects you quite a bit away but you weren't going that fast so you are okay.

Answer 2

Did you see the flash? If not, don't sweat it.

Answer 3

You probably got away with it.  

It how fast your going where its aimed at.  But some times the speed trap and the camera can be a 100yards apart.

And if this was at night did you see a flash?