The CCTV footage shows the clothing and hat that he was last known to be wearing.
In the footage, an apparently cheerful Finau is shown chatting with the bus driver, patting him on the shoulder and shaking his hand before waving as he leaves the bus.
Police said they had made extensive inquiries but had not been able to determine Finau's movements after this time.
Police said they had serious concerns for his welfare given how long he had been missing.
Detective Sergeant Rob Kerr said Finau's son was very distressed by his father's disappearance.
"We are doing everything we can to work out what has happened to Atonio Finau to give his family answers.
"There is nothing to indicate that foul play is involved, however given that there has been no confirmed sightings of Atonio after he was at the New Lynn bus depot, he could have travelled anywhere and we aren't able to focus on one particular area."
Finau was only reported missing to police in early December, which made the investigation much harder, Kerr said. Further CCTV enquiries had not been successful.
"We are still hopeful that we will find Mr Finau. We are hoping that someone remembers speaking with him or recalls seeing him in the New Lynn or surrounding areas on the 16th November or afterwards."
Anyone with information is asked to contact Police on 105, quoting file number 211203/4366.