The methodical determination with which Wolfgang Staehle tests the boundaries between reality and representation recalls two quite different traditions: conceptual art and the classical aspiration to achieve literal truth through mimesis.

His exhibition at Postmasters, which closes this weekend, consists of four photographic landscapes displayed in different formats. Dominating the main gallery space are a pair of large-scale projections: one of Midtown Manhattan viewed from Brooklyn, the other of the Hudson River Valley – a shot that recalls the magisterial vistas at Frederick Church’s estate, Olana. In a smaller display in the foyer, there is a view of the Teton Range in Wyoming. In all three projections, still images unfurl every 10 seconds to a new shot within the same frame.

In a third space, Mr. Staehle screens a film of Niagara Falls from the same vantage as a Church painting (not the better-known panorama in the Corcoran but the version in Scotland’s National Gallery).While the movie adds sound to the installation, it is not enough to brighten the pervasive monotony.

The still images look as if they could be a Powerpoint presentation of slides; they are, in fact, being transmitted live from the actual sites over the Internet. A similarly conceived project, staged in September 2001, with simultaneous views of Lower Manhattan, the television Tower in Berlin’s Alexanderplatz, and the medieval monastery of Comburg, captured the destruction of the World Trade Center, catapulting the New York-based German artist into the limelight. An earnest essay on representation and time turned into eerily riveting documentary footage – or, as the artist himself put it at the time, “my landscape painting became a history painting.”

Faint trepidation that lightning might strike twice gives a slight twinge to the otherwise banal, dutiful postcard view of the Empire State Building and Midtown. The image also gives a knowing nod to Andy Warhol’s notorious 8-hour, 6-minute, 1964 “stillie,” which showed nothing but the tower in real time. The irony of Mr. Staehle’s exacting experiments with duration and presence is that you don’t have to be there to get it, and it takes very little time to do so. Like a Powerpoint presentation, the conceptual “bullets” are all lined up.

Knowing that these images are “live” underscores the enervating realization that, aesthetically, they aren’t. Mr. Staehle’s projections are only painterly to the extent that looking at them is like watching paint dry.

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Pipilotti Rist offers an antidote to Mr. Staehle’s cerebral austerity with her kinesthetic video installation “Herbstzeitlose (Meadow Flower or Fall Time Less),” which fills the voluminous main space at Luhring Augustine. Both play with the conventions of tourism, but where Mr. Staehle merely references, Ms. Rist positively wallows.

Her installation consists of three simultaneously projected videos that often meld together or cast shadows from a hanging assemblage of plastic objects and packaging. The viewer can sit on garden furniture in front of a halfhearted mark-up of a Swiss chalet.

Swissness is certainly the pervasive theme here. A foot-high, cutout mountain range that might have been borrowed from the nation’s tourist board runs the length of the main projection wall. Videos pan Alpine scenery filled with upside-down cows and men plowing fields, or capture a young woman in traditional costume chewing plastic toys and yodeling. Just as Switzerland has its different official languages, Ms. Rist’s video is trilingual: the walls simultaneously transmit oceanic abstraction, picturesqueness, and surrealism: You can blend them together if you wish, or home in on one at a time.

Fluency and fluidity define what’s magic about Ms. Rist’s work. Left to their own devices, her themes are pretty tendentious – at one point, the plastic-car-and-cow-chewing blonde maiden transmogrifies into an African. Her landscape imagery is tastefully banal, like the arty opening footage of an indie movie. The soundtrack, a fusion of Eurovision Song Contest folksiness, trance, and baroque, is mesmerizing but is ultimately muzak.

What brings it all together are the rhythms of light, color, association, and movement, the faunlike way that themes and images skip along. When Ms. Rist’s wit and worldview are deprived of this natural flair for rhythm, as in the small installation “Tombstone for RW” in the back gallery, her art is correspondingly inert.

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Ms. Rist achieves Felliniesque moments; the British sisters Jane and Louise Wilson go for a Peter Greenaway meets-Jane Campion effect – quirky and sinister, but with sangfroid. Although “Erewhon,” their new video installation at 303,is a five-screen and five channel installation, its precision would be alien to Ms. Rist’s diffuse sensibility.

The action takes place in what seems to be a dilapidated boarding school, and perhaps in more than one time frame. One moment the building is fully operational, with morose though buxom, pallid young women in Edwardian gym gear doing calisthenics. The next it’s a wreck, reduced to a black scaffold grid. The work was made during a residency in New Zealand and set in a recently vacated sanatorium. We are told that it explores a period after World War I of government-sponsored eugenics programs.

The Wilsons favor resolute narrative structure (although without any overt storyline); clean, rich color; and a physical screen apparatus that mirrors the thematic imagery of the film. The multiple, parallel projections don’t take the emotions in different directions; rather, they reinforce a sense of confinement, enforcement, and individual loss of center.

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It seems gymnastics are the in thing with British women artists. While the Wilsons’ New Zealanders play gracefully among the high ropes, Sam Taylor-Wood, showing at Matthew Marks, floats, without visible support, in a series of acrobatic self-portrait photographs. To achieve this feat, she apparently had a bondage expert tie her up, then proceeded to Photoshop his equipment out of the picture. This left her artfully and effortlessly suspended in her sparse London loft.

Ms. Taylor-Wood is one of the original YBAs, as the British neoconceptual artists are called (her art-dealer husband represents Damien Hirst) and her aesthetics share a generational penchant for kinky coolness – big existential themes explored with knowing absence of affect and references to recent avant garde art. In an effort to emotionally up the ante, however, she embarked three years ago on a project to photograph Hollywood male actors crying.

The 28 thespians who have wept at her command attest to her persuasiveness: Ed Harris, Benicio del Toro, Sean Penn, Dustin Hoffman, Philip Seymour Hoffman, and Jude Law are among a star-studded cast of sobbers. For all that the project seems a pretentious artworld antic – celebrity as offshoot of literalism – it must be said that this relentless emotional artifice does elicit a strange, subdued, Bill Viola-like mild melancholia. It is like canned laughter that nonetheless puts you in the mood.