The 44-year-old Frankston man touched and filmed his three-year-old daughter in the shower in June 2020 and shared the content on Instagram in order to gain access to more child abuse material.

At one point during the abuse, she asked him: "Why?"

He responded: "Because I don't have many photos of you."

The father-of-three on Thursday faced the Victorian County Court, where he was sentenced to a total of four years and eight months in prison.

He had pleaded guilty to multiple charges including sexual assault of a child under 16, producing child abuse material and transmitting child abuse material.

The sentencing judge said the child abuse material he made of his daughter exists in perpetuity and may resurface any time.

"She was extremely young and vulnerable," the judge told the 45-year-old man, whose head remained bowed throughout the entire hearing.

"You were meant to protect her, but you exploited your position as a parent in order to satisfy your own depraved sexual purposes and transmitted the images for others to see.

"It was deliberate and calculated ... a shocking breach of trust."

The court heard the man's former wife described the impact of his offending as "devastating".

She said she lives "every day with guilt", would "forever feel responsible for not protecting her daughter", and worries about when the girl grows to understand what happened to her.

"While not uncommon for the innocent parent to feel guilt, the blame for your conduct is all yours," the judge told the man.

"You presented as a devoted and caring parent. Your conduct ... suggests you were anything but (this)."

The man's barrister previously said he was "deeply ashamed" and "acutely aware" he had ruined his relationship with his three children.

He will be a registered sex offender for life and must serve at least three years in prison before being eligible for parole, having already served 405 days in pre-sentence detention.

Australian Associated Press