The maximum available sentence was 10 years, and while Crown prosecutor Rebecca Guthrie sought sentence-deciding starting-point of four years for the worst offences plus two to reflect the totality, Judge Cameron accepted Mr Snell's call for a starting point totalling four-and-a-half years.
The judge rejected "discounts" for remorse or previous good character, making a deduction only for Harter's early guilty pleas, which alleviated any need for victims to give evidence to any court.
Ms Guthrie and Judge Cameron were concerned with what they saw as Harter's attempts in interviews to transfer some of the blame to the children.
Ms Guthrie said he appeared to have "some kind of expectation that the children, themselves, could have stopped this behaviour".
Mr Snell said Harter had suffered depression in bouts for much of his adult life. The latest was thought to have been triggered by the death of Belinda Harter with her partner and nine others in the balloon crash on January 7, 2012.
Outside the court, a production colleague of Harter also wondered about about the possible role of depression as he searched for an explanation, saying news of the offending came as a "profound shock", and that he had had "no idea" of what was going on.
"I could see the depression, but at the same time there was a kind of manic creativeness," he said as he waited for the sentencing, where about 12 victim family members dominated the public gallery.
As they listened, the partly balding Harter, dressed in a dark shirt without tie, stood between two prison officers and focused almost unfaltering on the judge.
While victims' families were in court, no victim impact statements were read, although the judge reiterated Crown assertions that impacts on the children were incalculable and long-term.
The girls had mainly revealed what happened to parents, friends or school staff, one girl having decided she no longer wanted to learn guitar because of what had happened.
In one interview Harter admitted he experienced sexual arousal while playing with the children, but he sometimes carried on with lessons afterwards as if nothing had happened.
Hastings investigator Detective Lisa Todd said afterwards the families were "devastated" but were not commenting.
A teacher with more than 40 years' experience in Masterton, Hutt Valley and Hawke's Bay, Harter is well known away from the career, particularly in musical and production circles.
He founded a theatre company in Wellington, he won awards for theatrical production, and he once appeared in a panel on a television programme helping students solve homework problems.
