A man who set up a video camera to catch paranormal activity ended up capturing his teenage son and partner engaging in intercourse.

The Tasmanian man set up the camera hoping to capture a ghost however forgot to turn the camera off.

When he returned from work the following day, he saw his partner and his 16-year-old son kissing and cuddling.

According to News Limited, he confronted his 28-year-old de-facto who allegedly downplayed the incident.

His son confirmed that he and the woman had had sexual relations at least three times in the previous days.

In a video recorded interview with police, the woman admitted to having sex with the boy twice despite knowing he was 16.

She was under the impression that the age of consent was 16 and was embarrassed about her conduct.

She pleaded guilty to five counts of having sexual intercourse with a young person.

Defence lawyer Steve Chopping told the court: "She accepts this is not a relationship which can or will continue.”

She and the father had been in a relationship for eleven years and had a child together. The relationship has since ended.

She has been remanded in custody and will be sentenced on Monday.