An accountant was sentenced to four months in jail for taking under-the-skirt photos of more than 35 women at Admiralty MTR station.
Lam Sai-ho, 28, pleaded guilty last month to 20 counts of disorderly conduct.
District Court magistrate David Dufton said the case was the most serious of its kind that he had come across, adding the offenses were planned.
The court heard Lam used his mobile phone to film up the skirts of victims, from June 28 to July 9, while waiting on platforms.
On July 9, a male passenger saw him holding his mobile phone close to his knee but it was angled under the skirt of a woman standing in front of him. The passenger was not sure if Lam was taking any photos, so he did not stop him.
However, he later reported Lam to the police when he found him wandering around the platform after the woman had left.
Officers found dozens of photos of the woman and a total of 201 under-the-skirt images on the same phone.
Lam earlier pleaded for leniency and said he deeply regretted what he had done. The case has also affected his family and career.
He claimed he had planned to seek help from a psychologist before being caught.
Dufton said Lam felt excited after taking photos for the first time and believed he could continue to ease work pressure by continuing to do so.
Dufton said yesterday easing work pressure was no excuse to keep on repeating offenses at Admiralty.
He added that Lam had downloaded an application onto his phone that made it less likely he would be caught while taking photos.
This showed his actions were predetermined.
Dufton said a medical report showed that the chances of Lam reoffending were medium to high.
However, considering his guilty plea, he was giving him a four-month jail term.
The maximum penalty for disorderly conduct in a public place is HK$5,000 fine and 12 months' jail.