Jesse Thomas, 44, was sentenced as a "serious sex offender" in the County Court at Ballarat on Friday.

Judge Howard Mason told Thomas his conduct was predatory and grossly exploitative.

"Your offending is very serious. Sexual assaults against children are unfortunately not uncommon and need to be deplored," Judge Mason said.

He said protecting the community from Thomas was the principal purpose for the seven-year jail sentence imposed.

The judge ordered Thomas serve five years in jail before he is eligible for parole. 

Thomas has already served almost two years of the sentence, having never applied for bail since his arrest in January 2016.

He will be a registered sex offender for life.

Thomas had earlier pleaded guilty to 12 charges, including four counts of indecent act with a child under 16, five counts of sexual penetration with a child under 16, two counts of producing child pornography and one count of possessing child pornography.

Thomas was in his 20s and living in Melbourne's western suburbs when in the mid-1990s he began to prey on a 14-year-old boy, who would later become his co-accused.

The two had met through friends and Thomas soon asked the boy to masturbate with him, telling him "this is what boyfriends do and this is how you show your love to people”.

They moved to Wendouree together and the sexual abuse stretched on for years, with Thomas encouraging his co-accused to watch pornography naked.

In 1999, Thomas’ co-accused, then 16, met an eight-year-old boy at Stockland Wendouree and gave him cigarettes.

The boy began visiting Thomas’ house before Thomas led him into his bedroom and sexually abused him. He used a Polaroid camera to take photos throughout the ordeal.

More than a decade later, Australian Federal Police officers found an online account on a child pornography website and linked it to Thomas’ co-accused, who later admitted to police his offending and implicated Thomas.

Ballarat police executed search warrants and uncovered more than 500,000 child pornography images belonging to Thomas.

Police found sexually explicit photos of the eight-year-old boy taken in 1999.

Thomas' charges related to his abuse against the boy and his co-accused.

Thomas’ co-accused, who cannot be named for legal reasons, was last year jailed for eight months.

A medical report was tendered to the court earlier this week, where a doctor stated he did not find Thomas' anxiety and depression contributed to his offending.

The court was told Thomas had a difficult childhood with his mother leaving the family when he was aged nine, while his father was an alcoholic.

Thomas, who has a spine condition, had not worked for 20 years and received a disability pension. 

He remained composed standing in the dock while he was sentenced.

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