Out of an elegant monogrammed case, antique dealer Phil Sunman pulls out an old-fashioned movie projector.

"It's a bit of a rigmarole to get it all set up," Mr Sunman remarks, as he lugs the heavy machine onto a table.

"But we got it going on Saturday night and ran a few of these films I've got through it.

"It's just the most amazing footage, there's Kingsford Smith arriving at Parafield aerodrome in a biplane with him in his flying goggles and paraphernalia."

The films of the Kyffin Thomas family capture a lost world. ( ABC News: Tony Hill )

Sir Charles Kingsford Smith achieved worldwide fame when he made the first trans-Pacific flight from the US to Australia.

The film of him was shot in 1931, and shows the Australian flying ace hopping nonchalantly from his plane, lighting a cigarette and chatting to an adoring throng — airport security and cancer concerns clearly belonged to a distant future.

But the rare, historic footage is not from one of the professional cinema newsreels that dominated in the 1930s.

Rather, it's a home movie, and the name on the projector case reveals just who was responsible for it: Evan Kyffin Thomas.

"The Kyffin Thomases, Robert and his wife Mary, were an interesting family," Mr Sunman said.

"They came out to South Australia on the [passenger ship] 'Africaine' in 1837 and became a society family. [They were] very, very well heeled."

Portrait of a wealthy media family

The Kyffin Thomas family brought a printing press to SA, setting up the colony's first newspaper, The Register.

Media, whether print or film, was clearly in the family bloodline, according to SA Library archivist, Jenny Scott.

"The Kyffin Thomases were to South Australia in the 19th century what the Murdoch family is to Australia and the world really in the 21st century. They owned the newspapers," Ms Scott said.

Evan Kyffin Thomas was one of Robert and Mary's grandsons. He shared his passion for film with his son, Rendel.

Together, they used the technology to document the life of extraordinary wealth and privilege enjoyed by the Adelaide establishment at the time.

As a result, the Kyffin Thomas collection features much more than up close and personal moments with Sir Charles Kingsford Smith.

Phil Sunman is collecting the films of the Kyffin Thomas family. ( ABC News: Simon Royal )

A family wedding from 1932, at the height of the Great Depression, shows guests bedecked in furs and top hats, arriving at a vast North Adelaide mansion in limousines.

It looks like an episode of Downton Abbey, except shot on the banks of the River Torrens. And, speaking of grand English houses, there's no shortage of them in the Kyffin Thomas films.

In those days it was customary for people of their class to make a trip back 'home' to London.

The films depict streets thick with double-decker buses and London's once infamous fog — a product of both the weather and coal soot.

There's a changing of the guard at Windsor Castle and a parade of soldiers at the famous Eton College.

A fragile world captured on celluloid

But the most revealing thing in these mid-1930s films are the carefree lives being led by the subjects.

The Kyffin Thomases, their friends and family all beautifully dressed, laughing, and strolling through gardens with a single cigarette in every hand.

Historic film reels and home movies shot by the Kyffin Thomas family. ( ABC News: Simon Royal )

What is most poignant about watching these people in 2018 is their blissful ignorance of Hitler's looming horrors: the war would wipe that world away.

Jenny Scott said it as the little details — clothes, cars, manners — that were often most telling in old films and photos.

"I think broadly it's what else that's in the photo or film that's most interesting to other people," Ms Scott said.

"So the subject might be, for the sake of argument, someone's Aunty Merle taken in 1954.

"That's nice for the family, but for me as an archivist it could be the shop across the road that reveals time and place, or a car that just happened to be in shot."

Mr Sunman has been progressively buying Kyffin Thomas films, and other memorabilia such as the projector, from a deceased estate over the past few years.

He now has a vast treasure trove, some of which he recently sold to a collector in Melbourne. The antique dealer knows most of what he's got, but he admits there are still some items he hasn't seen yet.

And while that old projector has bags more charm than an iPhone, it has none of the modern device's user friendliness.

Nevertheless, Mr Sunman sees a digital future for the Kyffin Thomas collection because celluloid base film, just like us, has a finite life.

Mr Sunman plans to digitize the remaining reels before time renders them unwatchable, closing a priceless window to a lost world.