Donald Mathew Capon was sent to jail for four years and six months after his sentencing on 18 child porn charges at the New Plymouth District Court on Wednesday.

A former teacher found in possession of more than 300,000 child sex images likened his fetish to collecting stamps.

During Donald Mathew Capon's sentencing on Wednesday, Judge Chris Sygrove said the probation report outlined how the defendant had a drinking problem and would often view child sex images while under the influence.

"You admit you used the images for your sexual gratification," the judge told Capon.

Sygrove stated Capon said the "thrill of the acquisition" of images was also something which motivated him, something the defendant compared to collecting stamps or pens.

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Capon, of New Plymouth, previously pleaded guilty to 18 charges, including multiple counts of possessing and exporting objectionable publications.

Following a tip-off from US authorities, the 50-year-old was found in possession of 382,025 images, 17,127 videos and 1,690 compressed files of children who were either partially dressed, naked or engaged in sex acts. Along with images on his computer, four hard drives and eight discs were found in his bedroom.

Capon's offending was first detected in November 2015, when he shared explicit images of children on a Canadian based chatroom called "pedo".

The defendant shared images and posted links to child sex abuse images on November 18, 2015 and on January 18 and 19 this year. Using different profiles, Capon also posted links to pornographic material on the website and also to a Slovakian-based cloud storage website.

After information was passed onto the New Zealand Customs Service, the internet address linked to the activity was traced to Capon's New Plymouth home.

On February 4, a search warrant was executed at Capon's address and customs officers seized his computer. During his interview, Capon admitted the authorities would find child exploitation publications in his possession and that he had used several online identities.

He told officers he collected child sex images and had an addiction to porn since 2002. Subsequent forensic analysis of the computer found child sex images dating back to 2001 and that Capon had imported photos the night before he was arrested.

During the hearing in the New Plymouth District Court, Crown prosecutor Cherie Clarke sought a jail term of five years and three months for the offending and asked Sygrove to impose a minimum non-parole period of 50 per cent of his end sentence.

She said two child victims linked to images found in Capon's possession had been located and identified by authorities. Clarke said it was people like Capon who "fuelled the demand for this type of material, encouraging sexual exploitation of children worldwide".

She said there was a high level of pre-meditation involved in the offending, which was illustrated by the sheer volume of images he had collected over the last 15 years.

Defence lawyer Susan Hughes QC said a minimum non-parole period was not required and Capon, who she described as "isolated, lonely and inadequate" had paid for his own therapy to address his issues.

She said her client had felt a "sense of relief" after his offending was discovered in February.

"He has never denied the offending nor sought to excuse it," Hughes said.

She said Capon was genuinely sorry for the offending and the shame it caused his parents, who were in court to support him. Hughes submitted an end sentence of four years imprisonment was appropriate, after taking into account Capon's early guilty pleas and his remorse.

Sygrove declined to impose a minimum non-parole period and said an important factor of this decision was information provided to him by Capon's psychologist who stated the defendant had never been a "direct offender" against children.

"You are adamant you never acted on the images that attracted you," Sygrove said to Capon, who has no previous convictions.

Sygrove granted a full discount for Capon's early guilty pleas and jailed him for four and a half years.

Capon will be eligible for parole in 18 months.

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