The Waikato dairy farmer who found a security camera in his milking shed says he thinks students or "greenies" are behind it.
Craig, who did not disclose his last name, was "horrified" to find the blinking camera aimed at the area where he places milking cups on his cows.
The farmer said the camera had been placed there late Thursday night, and he found it on Monday morning.
"I went to investigate it, I grabbed it down and once I realised what it was my heart sunk."
Craig said the footage didn't reveal anything of interest.
"All that was on it was footage of me doing my job. It was me milking putting cups on my cows in the morning, then me milking again in the afternoon."
He said the people who installed the camera weren't caught in the footage.
"They were too smart for that, they've got too much time on their hands."
Craig believes it was "uni students" who installed the camera; "greenies or do-gooders who just have no idea what farming is".
"There's always photos on them [university students] marching on the news - how about getting a real job and doing a job like the rest of us? They have no idea of real life."
He said people needed to remember it was the installers of the camera who were breaking the law, not him.
"It's trespassing. What gives them the right to come onto my property? If I went into their place, I'm sure they'd have a lot to say about that."
He said he was hurt New Zealand farmers were being "painted as monsters".
"I'm just an average daily farmer, I've had enough trouble with banks on our back, SAFE creeping round in the middle of the night ... It's people meddling in stuff they don't understand."
The farmer said the installers of the camera wanted to catch him mistreating his cows, but "they wouldn't find that here".
"We look after our animals. We love our animals. What we don't love is do-gooders saying we don't."
Craig said his cows were his pets.
"When cows are finished milking they'll come up to you and give you a kiss, and you can scratch them behind the ear, especially in smaller dairy farms like mine."
The Waikato farmer added that if he ever saw a farm hand acting cruelly he would definitely "ring his boss".
Craig added that he felt the New Zealand public had been misinformed about farming.
"We need to be represented in a better light, the media just make out that we're bad people, but we're the backbone of this country."
The farmer said he was working 70 to 100 hours a week.
"It's very hard to make a living - we don't take weeks off, or time off."
Waikato Federated Farmers president Chris Lewis said there had been a lot of rumours of hidden cameras, but this was the first confirmation that has come forward.
"How would you like a sneaky device around your property? I know what most New Zealanders would say about that."
Lewis said having unauthorised people walking onto farms posed a great threat to biosecurity.
"If they haven't changed their gumboots and their wearings they can bring a lot of bacteria and disease onto the farm.
"They could potentially do a lot of damage and cause veterinary treatment."
National board of farmers and health and safety spokeswoman Katy Milne confirmed working farms were "quite susceptible to new disease".
Milne said it was one of the reasons farmers needed to know who was entering their property, especially around cows.
The spokeswoman said people needed to remember farms were working environments, with a lot of hazards involved.
"Aside from the fact it's an invasion of privacy and trespassing, there's some pretty big safety issues involved."