A Canberra man who posted nude images of teenage girls on Instagram, and threatened young women into sending him more pictures, will spend nine months behind bars.

Oliver James Simonetti, 20, sobbed uncontrollably for more than 30 minutes in the ACT Supreme Court, as he was sentenced to two and a half years in jail, suspended after nine months.

He pleaded guilty to five charges, including using a carriage service to distribute child pornography material, and intentionally possessing child exploitation material.

The court heard the offences occurred in 2016, when Simonetti was 18 and 19 years of age.

Simonetti targeted three teenage girls, sending them photographs depicting themselves with little clothing on.

He then threatened to distribute the photographs unless more nude pictures were sent.

The court heard in one case, he sent a photograph to a teenage girl which showed her exposed breasts.

When she asked how he got the photograph, he replied:

"Revenge porn sites are great. Your life ends now, you have until my shitty internet loads to stop me."

In another case, he sent a photograph to a teenage girl taken when she was just 12 years old.

She was told she had five minutes to send back a full-body nude photograph, otherwise the picture would be disseminated.

'Worst category' of child abuse material found

The court also heard 700 child exploitation photographs were found on Simonetti's computers and mobile phone.

An analysis of the images identified 154 separate children.

While the majority of the pictures depicted sexually suggestive poses with no sexual activity, there were at least 25 images classed in the most serious category of child exploitation, which relates to sadism, humiliation or bestiality.

As he handed down his sentence, Justice Michael Elkaim noted Simonetti had shown remorse, accepted responsibility and had willingly facilitated the course of justice.

He said while Simonetti had done well at school, he had struggled to form strong relationships with his classmates, and suffered from depression and anxiety.

Justice Elkaim also read out a report from the man's psychologist, which said he had "developed a very good understanding of his actions [and] the effects upon innocent others" and that he had responded well to therapy.

Justice Elkaim said while the young man had no criminal record, he had committed an "objectively serious" crime.

"The three young women who were contacted were no doubt terrified by the messages they received and the possible realisation of the threats," he said.

"Every one of the 154 victims whose images have been disseminated have, simply by being depicted, been abused."

The court also heard a victim impact statement from one of the young women targeted by Simonetti.

She now sees a psychologist, had to take time off school, and was under so much stress her hair began to fall out.

Simonetti's two-and-a-half-year sentence will be suspended after nine months, and Simonetti will be on a good behaviour bond for two years after his release.