For Richard Billingham, whose fly-on-the-wall documentary about his family will be screened in Temple Bar tomorrow, the subject-matter of his work is not as important as the intensity the camera can confer on it, he tells Aidan Dunne

Richard Billingham's film, Fishtank, is, in more senses than one, a fly-on-the-wall documentary about his family at home in their Birmingham high-rise flat. He established his artistic reputation with photographs of his family, and the documentary is in many respects a natural extension of the still images.

Typically of Billingham, the title of the film, which has a public screening tomorrow night in Meeting House Square, Dublin refers not only to the fishtank but also to the flat itself. Within its claustrophobic confines, his father Ray, his mother Elisabeth and his brother Jason enact lives of circular routine that might seem extreme, but are, you realise, emblematic of life generally. So there is a sly implication that, far from being on the outside looking in, we are ourselves in our own fishtanks going round in circles.

The film was made in 1998 and has recently, courtesy of designer Agnès B (a long-time patron), been transferred to 35mm film stock, enabling cinema-scale projection. Billingham attained sudden artistic prominence in the mid-1990s when a book of his photographs of his family, Ray's A Laugh, was published. He was taken on by dealer Anthony Reynolds, and his work was bought by Charles Saatchi and included in the landmark Young British Artists exhibition, Sensation. He has exhibited widely since. But there has consistently been a great deal of debate about the nature and ethos of what Billingham was and is doing.

Initially this debate centred on the fact that he comes from what can fairly be described as a deprived, dysfunctional family. His father is a chronic alcoholic and there is a disconcerting rawness, a spartan, Beckett-like quality to the home life his work describes. The photographs were taken as references for paintings when he was at art school, but then became an end in themselves.

Fishtank came about through the desire to make short films suitable for screening in galleries. He shot a great deal of video with the idea of making short, separate pieces. A commission from the Artangel organisation led to the idea of putting a lot of this footage into one continuous work.

"There isn't a conventional narrative in the sense that everything stays the same," he says. "What I tried to do was to make it in the form of an emotional narrative, even a surreal narrative, you could say."

Like Billingham himself, who is watchful, quiet and self-contained, and has the knack of throwing you off balance with his wry sense of humour, his work hinges on careful, tactful observation and has consistently managed to wrongfoot the critics. No-one could argue with the force of his family images, with their formal cleverness and the way they draw us into a claustrophobic involvement with an enclosed internal environment on every level. There was, though, the question of sensationalism, even of exploitation of the subjects. But that is to assume that the artist was condescending to his subjects, and he has always been crystal clear on this point: he set out to make images as meaningful and as well as he possibly could.

He is a bit uneasy about people "looking at the subject-matter rather than the photographs". The distinction is important to him.

"Most people assume they can read photographs because they see them all the time," he says. "But usually what they mean is that they can see what it's a picture of, which isn't the point. You know, if I take a picture of a whitebeam tree, someone looks at it and says, 'oh it's a tree' - and then they lose interest. But that's only the beginning, really."

In any case, he flummoxed everyone by going on to make photographs that didn't feature people at all, studies of urban and partly rural Midlands landscapes. They are of fairly bleak places familiar to him from his childhood, but they are also, perhaps consciously, "photos minus sensational subject-matter". And, as he recalls, "people didn't know what to make of them".

He says he has never taken any self-portrait photographs but that "everything about me is there anyway when you look at the pictures". Never more so than in his images of empty places. While these seem to offer many ways in, they are spatially complex and ambiguous. There is an uncanny stillness about them, sometimes a feeling that these spaces are lost to us, impenetrably apart from us. Sometimes there is an acute sense of absence, a haunted quality that offers an intimation of the movement, people and noise that are missing.

"When you photograph something, you can imbue it with so much intensity that it becomes quite hyper-real - you don't see like that in real life," he says.

For him, "the landscape photographs are even more personal than the family photographs". There is an element of stereotyping in the assumption that a chronicler of inner-city life should not occupy himself making beautiful images of beautiful places, as though they were somehow foreign to him. In fact, just one of the surprising things about Billingham is that he is passionate and knowledgeable about nature. He was, he says, a fairly solitary teenager. One day, on a school trip to the museum in Birmingham, he found he had a little money left over, and a paperback called British Mammals caught his eye. He bought it, then thought nothing more about it.

"My parents are hoarders," he says. "They don't throw anything away, so there are these boxes of junk lying around. And a couple of months later, just to pass the time, I was going through one of these boxes and I came across the book. I thought, well, I might as well see what it's like. But when I started to read it, I could feel the hairs bristling on the back of my neck. I couldn't believe it. It was like I'd discovered another world, but one I sort of recognised."

Ensconced in his room, he read everything he could find on animals, plants and the countryside, pored over maps and guides. He wanted to know as much as he could "about how nature works".

His only concept of an artist was that of a Royal Academician. "I thought if I was a painter, I might hold down a regular job and paint a bit, and maybe when I was about 30 I might have a little exhibition down the road," he says.

When he began taking photographs it was always in relation to painting, not just that he intended them as studies for paintings, but in the sense that his visual references were paintings, his ideas on composition and structure.

"So I set up photographs like paintings. Then I found that the photos I was taking between these ones were more interesting," he says.

The subject of painting runs through his conversation like a stream that disappears and reappears but is always there, bubbling along beneath the ground.

"I always wanted to be a painter," he explains. He still wants to be a painter.

During his residency at IMMA, which ended last March, he worked on paintings, but - a refrain, this - he wasn't quite happy about what he was doing. Not quite, but almost. If he were to paint landscapes, he feels, he wouldn't use his own photographs as references. They are something in themselves, something complete.

"Painting is more demanding than photography," he says. "It's not even that enjoyable, but it's a more intellectual activity. You're analysing the whole surface all the time, your mind is engaged."

He has been taking many landscape photographs, in England, in India, in Ethiopia, in Ireland (he is planning to make a film in Galway) and, recently, in Italy, where he is in the middle of a six-month residency at the British School in Rome. Italy has prompted another change in his work. Uneasy with the effects of the light on the colour film he was using, he has turned to black-and-white. He has brought a tripod to the zoo and taken photographs of animals - a recognisable continuation, perhaps, from fishtank to cages. But he doesn't know as yet where all this will go.

"But that's all right," he says. "I think I work best when I don't really know what I'm doing, or when I only half-know what I'm doing."