A 26-year-old Tasmanian man who threatened to publish a picture of his girlfriend's breasts unless she had sex with him has been convicted of rape.

The Supreme Court in Hobart heard the pair had broken up frequently during a volatile relationship lasting four years.

The court heard that in the lead-up to the rape in March, the woman had admitted she had lied about becoming pregnant to the man and then losing the baby two years before.

On the night of the rape, the two had been communicating on Facebook when the man asked the woman for a picture of her breasts.

But when she sent him one, he threatened to publish it and send it to her workmates if she did not come to his house and have sex.

The jury convicted him on one of two counts of rape.

"(She) felt coerced to come to your home and have sex with you in return for you deleting that photograph," Justice Shan Tennent said in sentencing.

Justice Tennent said she was unable to accept a great deal of the victim's impact statement about the rape and its effect on her life.

The judge said the woman's claims that she felt "sick" as she got near the man's home that night were "entirely inconsistent" with what she told the court and her social media messages.

Justice Tennent said the woman had also said the first person she told about the rape was her mother when, in fact, it was male friend on the drive home.

The judge said she accepted the woman was now having difficulty with daily life and had sought counselling, but said there was no evidence to support her assertion she suffered Post Traumatic Stress Disorder as a result.

"This is not a case that involved an otherwise long and caring relationship that went bad on one night," Justice Tennent said.

"It was a relationship that was short-lived and generally dysfunctional."

Justice Tennent said the woman knew how to push the man's buttons and on this occasion had pushed it too far with terrible consequences.

"Having said that she did not deserve to be threatened by you, or to be pressured to have sex with you, in order to have a photo she sent you deleted," the judge said.

"You are not a sophisticated person who necessarily understood at the time that what you were doing amounted to rape.

"While you did not do it by physical violence, you did it by imposing your will in other ways."

Justice Tennent sentenced the man to two years and nine months in jail, ordering that he not be eligible for release until he has served at least half that sentence.