Thomas Ruff: Photographs 1979 to Present is at IMMA (01-6129900) from Friday until October 6th.

These days, museums and galleries of contemporary art are awash with large-scale photographic prints, most of them in colour. So much so, that we take the presence of photographs on the fine art scene for granted. But in fact it is a relatively recent, still contested phenomenon. One of the first of the current generation of visual artists to make the photographic breakthrough, and one of the most influential, is Thomas Ruff, and an exhibition that surveys his work, from his student days to the present,

He was born in a small town in Germany's Black Forest. The family was not well off, but his parents were determined that their children should have advantages that they had not had. He began studying at the Dusseldorf Art Academy in 1977, where Bernd Becher had recently taken up the position of professor of photography.

Becher worked in collaboration with his wife, Hilla. They had formulated a distinctive style of objective documentary photography, and built up a remarkable archive of studies of industrial buildings and installations. This may sound fantastically dull, but both the Bechers' approach and their photographs are fascinating. At the Dusseldorf Academy, a veritable roll call of now prominent photographic artists, including Ruff, Candida Hofer, Andreas Gursky, Thomas Struth and Thomas Demand attended their course, and in every case their mature work bears the Bechers' imprint in one way or another.

When Ruff first saw the Bechers' work he was completely taken aback. Their precise, forensic, unemotional images contradicted his ideas about art photography. He concluded that his own approach was hackneyed and superficial, and gave up taking pictures for more than a year.

Part of the Bechers' methodology was to pinpoint their subject and apply themselves methodically to it. Partly inspired by Eugene Atget and Walker Evans, Ruff's first subject was the domestic interior, that is the ordinary petit bourgeois Interiors in which he and his contemporaries grew up. He quickly realised that, while the Bechers worked in black and white, he wanted to use colour.

His plain, bland photographs of unoccupied domestic spaces are curiously hypnotic, and their influence is still apparent in current fine art photography, not to mention style photography in general. In a similar vein he went on to photograph apartment buildings in his Houses series.

It was, however, his Portraits that established his reputation. In them, he applied the careful neutrality of the Bechers' photographs of buildings to human beings; to his fellow students, in fact. When one of these, printed on a large scale, was bought by the Frankfurt Modern Art Museum (prior to its opening) in 1987, it marked something of a breakthrough for German art photography - and for Ruff.

By the following year, he was able to eschew commissioned projects and devote himself to his own work.

The Portraits, particularly when printed on a large scale, are strange, disconcerting documents. Their studied blankness is widely perceived as relating to a loss of faith in the veracity of the photographic medium. The image we see, as Ruff put it once, is something constructed by the person behind the camera. He questions our assumptions about perception and photographic images as a reflection of reality. Faced with one of his ostensibly ordinary images, "the closer you look, the less you recognise". So his portraits are much more about how we go about making and looking at portraits than they are simply portraits.

It is logical, then, that for much of the time he has made images of images, sometimes making extensive use of digital manipulation.

And looking at his work, you can see the truth of his claim to be influenced by three kinds of photograph: the postcard, the passport and press photos, all of which are characterised by implicit codes and conventions.

His stance is sceptical and interrogative. For example he amassed an archive of printed Newspaper Photographs, edited it down to 400 images and printed them all enlarged twice over. The abiding question is what remains when these newspaper images are decontextualised and represented without explanatory text - apart, of course, from the fact that they become images selected by Ruff and embark on new lives as art objects.

Long a stargazer, for his Stars series he made prints of negatives from the archive of the European Southern Observatory, organised into groups according to his own arbitrary criteria. For his Nudes, he embarked on a systematic study of Internet pornography and used downloaded images, which he then blurred electronically in a way that strongly recalls painter Gerhard Richter's blurred paintings. In adopting the pictorial conventions and fuzzy appearance of amateur photography some decades earlier, Richter famously problematised the photographic image, and appropriated it for painting. Here a photographer re-appropriates an appropriated photographic device.

Blurring porn is a way of delaying or diverting what Matthias Winzen, in his essay on Ruff, terms the "pre-rational" power of the image. But, as he goes on to point out, pornography is an extreme case of something intrinsic to all photography, in that it disembodies the gaze and prioritises the image over the thing depicted. Thanks to our "visually greedy and easily deceived eyes", possession, power and control of the photographic image stands in for possession, power and control of objects, places or people.

Even when engaged in apparently more direct projects, Ruff has managed to prioritise the image and distance himself from the referent at the end of the signifying chain.

Unable to travel to photograph a building for a series on the work of architects Herzog and de Meuron, he had another photographer send him photographs which he then reworked with a computer.

There is an emotional coldness to his images and an intellectual austerity about his conceptual schemes that can be forbidding. But he doesn't really do humour, at least in his work. When he tries, with a series of satirical collages, the results are awkward and heavy-handed.

I think his best works are the Portraits, Interiors, Houses and more generally the architectural photographs, plus the Nudes. But it is no exaggeration to say that for anyone with an interest in contemporary art, this show is nothing less than essential viewing.

A gallery talk on Thomas Ruff: Photographs 1979 to the Present takes place on Thursday at 11.00 a.m. at IMMA.

Booking essential