A music teacher at a top independent school secretly filmed himself sexually abusing teenage pupils while pretending to measure them for their school uniforms.
A court heard that Phillip Evans, who taught at King Edward's School in Edgbaston, Birmingham, also installed high-tech equipment to film other pupils in changing rooms and showers and downloaded around 350,000 indecent images of children.
The sexual abuse, which took place at a cadet store room at the school, came to a light after police raided his home in August this year.
Evans, 38, of Selly Oak, had previously admitted six charges of voyeurism, seven of indecent assault, seven charges of making indecent images and one of taking them.
Jailing Evans for three years and eight months, Judge Peter Carr said: "This behaviour by you was repulsive, disgusting and deceitful.
"These offences were committed by you in gross breach of trust. Parents of pupils and pupils themselves should expect that a school is a safe environment. You made the environment unsafe."
Birmingham Crown Court heard that Evans was also the RAF leader of the Combined Cadet Force at the school and that he had filmed some of the children who were on a summer camp at RAF Coningsby in Lincolnshire.