A driver fears that dozens of motorists are being nabbed on Mansfield ring road since the speed limit was dropped to 30mph.
Supply teacher Andrew Abele ended up with a £580 court bill and 16 penalty points on his licence after being convicted of four counts of speeding.
He was allowed to stay on the road.
Three incidents were on Rosemary Street where cameras clocked his Jaguar over the limit three times in two months.
After the hearing at Nottingham Magistrates' Court, Mr Abele said: "If this helps to stop people being caught, I am fine.
"Let's make those cameras cost more to put in than the revenue they create. If my fine helps someone else, that would be absolutely fabulous."
The court heard that his car was first filmed on Rosemary Street on November 29 doing 36mph.
On December 1, the speed was 42mph. On December 12, it was recorded at 36mph.
He was also found guilty of doing 39mph on the A6191 Chesterfield Road North, Mansfield on February 4. That is another 30mph highway.
Police civilian worker Chris Foster told the court that the street is in a built-up area and that 30mph signs are not ordered by law. But he said that blue lights would be used when mobile speed cameras are in action.
The Rosemary Street stretch is now covered by cameras which calculate the average speed of drivers. Mr Abele said that led to some motorists being seen to slow down as they tried to work out the speed after entering the zone too quickly.
He said local people may have been caught by the drop in the speed limit, telling the court: "In my memory it is 40."
District Judge Tim Spruce decided not to impose an immediate ban, which can be ordered when the points total reaches 12.
He said that a disqualification would hamper his prospects of getting work as a supply teacher and make it harder to help his partner's 93-year-old mother.
But the judge warned Abele of Alfreton Road, Sutton, that he would not be able to use the same argument again to avoid a ban.
"You are effectively driving on eggshells. It is an expensive business, speeding," the judge added.
Tony Wilkinson, prosecuting, said that all four incidents were recorded on roadside cameras. All the paperwork was sent to Abele within deadlines.
Abele was fined £400 with £150 prosecution costs and a government surcharge of £30.