Sex offender Alan Rubick was highly manipulative and skilled at identifying young vulnerable boys.
"He twisted their view of life and encouraged them to believe what was occurring was innocent and acceptable," crown prosecutor Harry Mallalieu told the High Court in Wanganui yesterday.
There was evidence of psychological manipulation and premeditation and threats to prevent reporting, Mr Mallalieu said.
Rubick was yesterday sentenced to preventive detention with a minimum non-parole period of eight years on a raft of sex charges against young boys aged 7 to 14, and 20 charges of possessing objectionable material. The offending occurred in two periods, between 1995 and 2001, and 2012 and 2013.
Rubick showed the young boys pornography, engaged in masturbation and oral sex and some of the acts were filmed. At times he provided them with drinks, lollies and food. Police found 12,157 objectionable images in his possession.
Victim impact statements read to the court spoke of the disgust and hate for Rubick and the ongoing effect - including anxiety, depression and nightmares - his offending had caused.
"That's something I'm going to have to live with for the rest of my life. The mere thought of you makes me feel sick," one said.
Another called Rubick a "disgrace to the human race".
Rubick sobbed on occasion in the dock.
Defence lawyer Stephen Ross said Rubick was aware of the long-term harm suffered by victims.
"He has instructed me to apologise but he accepts that apology is unlikely to be accepted and nor should it be. At this point in time there is nothing else he can offer," Mr Ross said.
"There is no doubt this is serious offending, all the aggravating factors are not denied."
In sentencing, Justice Ron Young acknowledged Rubick's guilty plea but said he showed little remorse.
Rubick had said the offending happened at times of stress in his life. "Frankly it provides no explanation whatsoever for your offending," Justice Young said. "What you describe is nothing more than the ordinary ups and downs of adult life."
Rubick admitted the offences only when video evidence was found. The judge said the offending rate seemed to have increased over the years and considered the risk of his reoffending was medium to high.
Justice Young said Rubick was skilled at identifying vulnerable boys - "There are eight boys' lives who you have seriously compromised."
He sentenced Rubick to a minimum eight years imprisonment for the sex charges and two years for possession of objectionable material, to be served concurrently. He also ordered the destruction of computer hardware.
All details relating to the victims and the location of the offending have been suppressed.