Jonathan Thomas Watson, 21, from Harrogate, videoed one woman as she was getting changed in a cubicle at Knaresborough Swimming Pool.
York Crown Court heard that he placed his mobile phone on the top of the cubicle in a unisex changing room.
The woman, in her thirties, was unaware she was being filmed until she saw the phone perched on top of the cubicle, said prosecutor Matthew Collins.
Watson filmed six other females at a property in Knaresborough using similar covert means.
The teenagers were said to be distraught after discovering they had been secretly filmed while using a bathroom.
Mr Collins said the woman at the swimming baths, who was half-naked, was “angry and shocked” when she realised she had been filmed after showering.
Police were called and arrested Watson at the baths. They then went to his home and seized computer equipment and his iPad on which they found intimate video footage of the young women.
When asked about the videos, Watson told police he was just “mucking about”.
Officers found eight such videos on his iPad which had been backed up on Watson’s computer.
Six of the videos had been made at a property in Knaresborough where Watson had covertly filmed the teenagers in a bathroom.
Two further videos showed another female getting dressed.
Watson was charged with seven counts of voyeurism and ultimately admitted all the offences after making initial denials. He appeared for sentence on Friday.
Mr Collins said the woman who was secretly filmed at the swimming baths could no longer bear going to the pool and her confidence had been shattered by Watson’s despicable offences.
All the victims had been “unnerved” and deeply affected by Watson’s warped behaviour, which occurred over a period of nine months.
Mr Collins said there was “an element of planning and concealment” in the way that Watson had videoed the females.
Defence barrister Richard Canning said Watson was a “socially-isolated young man” and was “embarrassed” by his actions.
He said Watson had never been in trouble before, was a working man and had a supportive family.
He added that Watson was “petrified” of going to jail and would lose his job at Wetherspoons were he to receive a prison sentence.
Judge Simon Hickey told Watson: “You clearly knew what you were doing (and) you clearly planned what you were doing. There were no fewer than seven victims, all recorded without their knowledge.”
Watson was jailed for six months and ordered to sign on the sex-offenders’ register for seven years.
He was also made the subject of a sexual-harm prevention order, which will last for 10 years.
PC Stephen Peachman, who led the case for North Yorkshire Police, said: “Not only were Watson’s actions warped and illegal, they were also harrowing for the women he recorded.”