Jeannine Alton sees undercover film shot in Budapest bathhouses and other new work on show at Oxford's Museum of Modern Art

The three new shows at the Museum of Modern Art demand a fair measure of flexibility from the viewer. In the Lower Galleries Alison Turnbull has a series of cool intriguing paintings. Her title Houses into Flats comes from a post-war handbook for just such a conversion but she extends the idea to a wide range of buildings.

Plans and charts become general statements without losing their original definition. Their titles give us a firm, but laconic, pointer: Prison, Bank, School, on which memory and imagination can work. Castle is dominated by its formidable circular keep, Prison and Bank are equally tightly enclosed, Spa drowns in saturated blue, Lighthouse whirls like stars, Airport (from a drawing of Tokyo airport taken from the internet) formalises corridors, plane parks and departure bays. Factory is fascinating: apparently a German wartime underground building left unfinished as the Allied advance caught up with it, it is transformed into elegant curves of brown on grey. Grain Elevator turned the vast silos of the American Midwest into a symmetrical pattern of circles in the sunny gold of harvest.

Meanwhile in the Upper Galleries the Polish installation artist Katarzyna Kozyra brings a whole new dimension to bums on seats with her videos of bathhouses, women's (1997) and men's (1999), both shot in Budapest with secret cameras. Filming took about a fortnight, cutting and editing much longer. Kozyra herself was present. In the women's bathhouse she carried her camera concealed in a plastic bag (hence presumably the occasional swoops and swings), for the men's she had herself disguised with a lot of body hair and a set of genitals "cast from a male friend" to quote the visitor's guide. Good grief, what next. Is this today's equivalent of Turner lashing himself to a mast to observe a storm at sea?

The ethical/artistic implications are far from risible. To achieve a record of people "acting naturally" (and do they, incidentally, even in a bathhouse?), she has used strangers without their consent, and in a double deceit has forced us to collude with her in voyeurism. The rigorous editing process too has added a blurred echoing soundtrack but obliterated genuine conversation.

Time deals more harshly with women, and the intercutting of female icons by Rembrandt and Ingres is a wincing reminder, as they apply creams and lotions, or enjoy a gossip. In the men's premises the bleak metal benches that flank the pool (illustr) enhance, Hopper-like, the solitariness of the figures sitting or in aimless perambulation. The sexual and social encounters aren't apparent.

Kozyra's latest work The Rite of Spring is based on just 30 seconds of Stravinsky's score and Nijinsky's choreography, re-created by naked male dancers and shown on a montage of video screens as an animation, speeded up to intensify its mythic force.

Down in caf MOMA John Harland's New Paintings combine vivid colour and graphics in the manner of the young Hockney. There are titles here too, of places, Naples, India, Africa, and of people, Leonard, Louis, Tina Brown. One of them "Lovely colour" will do for all, as vermillion, turquoise, scarlet and Prussian blue riot.

Harland's and Turnbull's work remains till April 22. On March 7 the bathhouses will close, and on March 11 Mark Lewis's film installation, North Circular Road "a critique of cinema" opens in the Upper Galleries.