The court was told that the man had been living with his wife in Johnsonville.
Shortly before her two daughters moved in with them, he installed a hidden digital camera pointed at the shower.
He told his step-daughters the plug was blown and not to touch it.
Sharon said the man had been the baby of the family, smart and private-schooled. But his offending had gone on for 12 years and if the DVDs hadn't been found, he could still be doing it today.
The man was ordered to attend a psychiatric assessment, not to possess a computer, not to associate with people under 16 years, and not to associate with his victims. A protection order to stop him seeing his step-daughters was also issued.