Authorities are hailing the court decision as a win for the environment.

The 37-year-old woman and 33-year-old man shot onto Parks Victoria's radar when they appeared on cameras secreted in the Metcalfe State Forest.

Investigators noticed them on secret surveillance cameras before raiding their property with the help of police and the Game Management Authority.

The raid unearthed a diary with "Firewood 2022" on the cover, giving investigators insights into an unlawful firewood business.

Authorities also seized 18 cubic metres of timber, two chainsaws, a box trailer and a block splitter.

Each has received a $1500 fine for illegally cutting, removing, and selling red stringybark timber, dumping rubbish and damaging wildlife.

They have also been ordered to forfeit tools and machinery used in their crimes.

The conviction is not the first using concealed cameras in the Metcalfe State Forest.

Investigators notched up a win in February after a 39-year-old man pleaded guilty to two illegal firewood theft offences in Bendigo Magistrates' Court.

He too had shown up in covertly filmed forest vision.

Parks Victoria ranger team leader Mathew Sobey hailed the latest convictions as a win for the environment.

"It's heartbreaking to see old-growth trees chopped down and their habitat values destroyed by illegal firewood operators seeking to take advantage of unsuspecting Victorians," he said.

"The court's decision sends a clear message that illegal firewood theft is unacceptable."

People can legally source firewood by collecting it themselves from designated firewood collection areas at designated times during the year.

They can also buy it from reputable sellers.

You can report illegal firewood theft or suspicious dealers to Parks Victoria on 131 963 or the Conservation Regulator on 136 186.