Wolfgang Tillmans

When the German-born artist Wolfgang Tillmans was awarded the Turner prize in 2000, the response was unusually sharp. How could a photojournalist possibly win? At 32, Tillmans had made his name shooting London's street culture, the rise of Gay Pride, the nightlife of the clubbing generation. He worked for the Face and i-D. The studiedly casual authenticity of his photographs was just an exercise in style, tedious and underpowered. Some insisted that Tillmans was not even an artist.

His installation for the Turner prize show was striking for being simultaneously slight and immense. He showed hundreds of photographs, mounted all the way from skirting board to ceiling. They came in 57 varieties of format: Polaroids, photocopies, inkjet prints, cibachrome panoramas in saturated colours. They were framed, unframed, magnified, cropped, minuscule and the size of a billboard. They showed passengers on the tube and pedestrians in the street, clothes drying and flowers wilting, insects, bottles, off-duty models, friends and fellow clubbers.

And they were as boring as they wanted to be – or so it seemed to me. Tillmans had no style but every style, no particular subject but everything around him. It was therefore crucial that his images be shown in quantity. And the installation resembled nothing so much as a set of magazine layouts with the text stripped out. No captions were necessary, after all: the photographs, however demotically, spoke for themselves.

Ten years later, Tillmans is not so much intensely fashionable as internationally acclaimed. He has had museum retrospectives all over the world. His focus is less local – though there are still images of his studio door in Bethnal Green, a dosser in Mile End, a little boy walking across an East End housing estate – and more global, even planetary. Collectively, the images feel stronger and deeper.

Tillmans is interested in the skin of the world, the way it changes over the years. A baby travels in a car seat inside a vehicle, hermetically sealed within both bubbles. A woman runner, hands tensed, stands lost in a field of corporate symbols. A vast photocopy, grainy and black, shows a man sleeping in a park, although it might as well be the edge of the world so voluminous is the enveloping darkness.

I saw the pictures ahead of installation, arranged in his studio according to the plans for the show. The photographs are grouped in families – social scenes, quasi-portraits, abstracts, architectural details, events in nature and the cosmos. As a boy, Tillmans was fascinated by what he saw through his telescope. Thirty years later, he takes it up again, attaching a camera lens to one end, to photograph the passage of Venus across the face of the Sun for the first time in more than 100 years.

The images are modest – a rosy disc flecked with a tiny dark spot – and they come in interrupted sequence so that one has a sense of the photographic process taking place, the difficult contingencies involved in recording this spectacle. Nearby, an exquisite photograph of the night sky seen from a plane window that resembles nothing so much as a Japanese watercolour includes a number of stars that are introduced by the camera itself: particles of evidence from the inner world of this mechanical object.

It is clear that the low-content look that characterised previous shows is to some extent a thing of the past. All that egalitarianism surely had to be something of a myth in any case: not all subjects turned out to be equally interesting. Tillmans has a sense of the wondrous like anyone else and this is reflected in photographs of adamantine dewdrops and mysteriously dense forests where there is no obvious point of entry for the eye. And it is there in the words of a newspaper cutting included in a potent array of documents: "Astronomers believe there are more stars in the universe than grains of sand on Earth."

The abstract works in the show are simply sheets of glossy photographic paper saturated with colour and mounted in Perspex boxes. Planes of light, they look – of course – like abstract paintings, but with a slight crease or fold they acquire the dimensions of sculpture.

A sheet of cerulean blue is gently indented in the middle and immediately its radiating creases reflect white like vapour trails in the sky. A black surface becomes a coldly gleaming mirror when you stand before it. Studies in the behaviour of light and colour, these minimalist works are undeniably beautiful. They go with his photographs of sheets of photographic paper curling back on themselves in the elegant shape of a teardrop.

It is crucial that these abstract works are photographs and not paintings, that the events they record – the spontaneous interaction of light, chemical and paper – are not created but only set in motion by Tillmans. If this show has a unifying theme it is the pure elements of photography, everything from drawing with light itself, to magnification, depth of field, developing and the many varieties of printmaking.

But, above all, the peculiar status of photography itself: the way that a photograph may seem to flatten substantial forms into floating ectoplasm within a landscape, the way that a photograph of an old master painting taken from an odd angle can transform the subject – in this case, William of Orange – into a less imposing figure, almost a contemporary friend.

The way that a photograph can fail to comprehend, or convey, what was there before the lens: was it a bit of fabric or a metal surface; was it a slice of agate or some sort of ancient dust, internal to the camera itself? Tillmans sometimes seems to be getting at something rare and almost too slippery to be held, namely the moment before a fragment of reality recorded on photographic paper resolves into a definitive picture.

The Serpentine gallery show feels pensive and considered. You see an unnamed border with guards, a house with one side demolished, a man deeply absorbed in trying to pick a splinter from his foot. You see an almost classically boring picture of a half-open window. Where you are, who's depicted, what exactly you are looking at: the answers are not always declared in the images.

And although there are sumptuous works here, Tillmans is never as preoccupied with the retinal as he is with the conceptual. He is drawing your attention to the making, and viewing, of photographic images more than the things they depict. This is a subtle and complex enterprise, but not without its risks. I would not want to overstate, in the end, the pleasure of looking at his pictures.