So far so good. The only problem is with the show itself, or at least with significant parts of it. Walk into the Tate's upper galleries and you will find yourself assailed by the ever less heady smell of rotting carrots, part of an installation by the Georgian artist Gia Edzgveradze called Situated in the Eclipse (Do you mind it honey?) Dark and light being something of a double act, Edzgveradze takes duality as his theme: his installation consists of two rooms, one light and one dark, each with its floor subdivided into a checkerboard of alternating dark and light squares. The dark squares in the first room consist of carrots, prettily arranged in shallow mounds; Edzgveradze has made his light squares by repeatedly painting the word "hopes" in cursive script on the gallery floor. On one wall, a projector casts a moving image of the unclothed artist doing a vigorous breast stroke on his bedroom carpet while quacking the word "free"; on another is projected a slide of Edzgveradze, naked and on all fours, with a carrot in his mouth and another up his bottom. In the second room, the floor-squares are, in turn, growing grass and highly polished metal. One wall bears a painted tableau of ping-pong players - table tennis being "binary, duality, a sign of vitality itself" according to the artist - while the room is topped by a frieze of gnomic inscriptions along the lines of "What's matter, honey?" and "Don't take it serious, honey."
You cannot help but agree with the latter exhortation, for Situated in the Eclipse is as big a pile of tosh as you are likely to find this side of Penzance. Talk to Edzgveradze and he will explain to you how carrots grow in darkness and grass in the light; how the journey from room 4 to room 5 is thus an allegory of the journey of the human soul, and so on. Carrots, adds one Tate curator, grasping at exegetic straws, also help people to see in the dark. As the carrots rot and the grass grows, so the polarities between dark and light will become ever more apparent to the eye (not to say the nose). And so on and so on.
If a piece of conceptual art is to work, then it has to do at least one of two things. Either, like an abstract painting or a piece of music, it must carry some kind of inarticulable numinous charge; or, like a code or puzzle, it must engage the viewer on an intellectual and acrostic level. I know that Situated in the Eclipse is trying to say some bleak, Godot- ish thing about, oh, let's say the triumphant pathos of the human condition; but frankly, its message is lost in the embarrassment of reading it. The work is simply too heavy-handed in its conception, too laboured in its metaphors. Given that Edzgveradze has not merely been chosen to exhibit in the Tate but to represent his country at this year's Venice Biennale, the message which Situated in the Eclipse conveys all too clearly is of the occasionally woeful state of contemporary curatorship. The real sadness is that many of the holiday-makers who visit "As Dark as Light" over the summer will be the kind of people who have been raised on bogey-man stories of Carl Andre's bricks. They are likely to leave St Ives with their anti-Tate prejudices firmly intact.
Still, there are reasons to visit Cornwall over the summer. Some other participants in the Tate's show vary from the polite to the possibly good. Yuko Shiraishi's Judd-like installations of sculptural paintings, Eclipse and Blue Deference, are hardly likely to set Porthmeor Beach alight, but the former work - a gradated series of black-edged yellow boxes - is at least pleasant to look at, and the thought of its transformation at the moment of total solar darkness on 11 August is intriguing.
Gill Clarke's apocalyptic dance piece, Partial sitings: full view, made highly effective use of both the Tate's architecture and of the tension between individual and choreographed expression. Each of her dancers spun and whirled through the gallery in a movement that was at once entirely self-enclosed and part of a greater whole: a neat enough analogy for the music of the spheres, and one that the piece did not labour.
But the real reason for visiting St Ives International is to be found later in the summer at Newlyn. There, the American skyspace artist James Turrell will install an observatory-cum-light-sculpture called Arcus and another eclipse-specific work overlooking St Michael's Mount. Sightings of Turrell's work in Britain are about as rare and uncanny as solar eclipses; whatever your feelings about the latter, Turrell is definitely worth the journey.
Call it coincidence, but the number of shortlisted artists using film in their work has grown dramatically since Channel 4 took over sponsorship of the Tate Gallery's Turner Prize nine years ago. Last year, two of the finalists submitted video installations. This year's shortlist, announced last week, includes three artists who work with film: four if you count the endlessly autobiographical Tracey Emin, who uses photography in her mixed media constructions. The other three are Steve McQueen, whose film Deadpan, was shown at the ICA earlier this year; Steven Pippin, best known for his photographs of laundrettes; and identical twins Jane and Louise Wilson, whose four-screen video Gamma was shot at Greenham Common. One of the prize's jurors suggested that "including a painter in the shortlist just for the sake of it would have belittled their work", another that "the question of medium has become less important" - just so as long as it is film, apparently. And although the Turner Prize rewards British contributions to the art scene, it is less and less the art scene in Britain: Emin's major 1998 show was in Tokyo; Pippin's in San Francisco, and McQueen, for his part, has moved to Amsterdam.
'As Dark as Light': St Ives International (01736 333 0240) to 31 Oct; note: Tate St Ives' shows end on different dates (01736 796 226). Turner Prize exhibition: Tate Gallery, SW1 (0171 887 8000) 20 Oct to 23 Jan 2000