DON'T LET the scaffolding fool you.

Despite closure of the Phillips Collection's Goh Annex while the museum expands into a new building next door -- scheduled to open in 2005 as home to the Center for Studies in Modern Art -- signs of life have been spotted on the second floor of the original house. In that sweet, old space, opened by Duncan Phillips as a museum in 1921, you'll find three small, chamber-size exhibitions, none of which has any special correspondence with any other, but each of which is quintessentially Phillipsian.

Considering that two of the shows feature photography, a medium that Phillips Collection director Jay Gates describes as a kind of "blind" spot in Duncan Phillips's collecting history, this may strike some as an odd statement. Yet the kind of photography on view -- focusing on the one hand on the landscape, and on the other on gestural abstraction, both mainstays of Phillips's painterly fixations -- dovetails perfectly with the museum's institutional aesthetic. Coupled with the fact that the Phillips has, in more recent years, started to become known as an occasional venue for some top-notch photo surveys and retrospectives, the three shows are a perfect fit.

Of the group, "Aaron Siskind: New Relationships in Photography," which pairs Siskind's black-and-white photos of peeling walls, asphalt cracks, graffiti and washed-up seaweed with the work of such abstract expressionist painters as Franz Kline, is my favorite. "August Sander: Photographs of the German Landscape," which focuses not on the artist's well-known portraiture, but on pictures of trees and streams, almost all made during the politically charged decade of the 1930s, is a close second. The one exhibition that actually breaks some news, "Revelation: Georges Rouault at Work," probably rocked my world the least, despite the discovery by conservator Marla Curtis (a former Phillips conservation fellow now with the Museum of Fine Arts, Boston) that the French painter painted exclusively on paper -- and sometimes on top of his own prints -- before affixing them to backings of canvas or other material and then reworking them.

While it may hardly sound like a stop-the-presses disclosure, this insight into Rouault's working (or should I say reworking?) methods makes a difference. Thanks mainly to high-magnification stereomicroscopy and infrared "transmittography," which enables one to "see through" the paint to the underlying, carbon-based printer's ink, it's an important breakthrough. This is true not only for conservators, for whom it might be useful to know that a substrate of fragile paper lies beneath the often thickly impastoed paint, but to art historians, who up to now have given only short shrift to the relationship between the artist's paintings and his graphic work. But, as Curtis and the show's other co-organizer, Phillips curatorial coordinator Hannah Byers, write, "This exhibition is only the first step in examining this aspect of Rouault's oeuvre."

It isn't, however, the somewhat premature nature of the show's "revelation" that leaves me cold. I've never been a huge fan of Rouault's work to begin with. On the one hand, the cartoonishness of his flat, starkly outlined and boldly colored figures appeals to me, yet their evocation of pictures in ecclesiastical leaded glass -- Rouault first apprenticed with a stained-glass maker, then with a stained-glass restorer -- feels uncomfortably decorative, not to mention oddly emotionless.

Siskind's work, on the other hand, has a kind of timeless beauty, along with a social realist's sly commentary. Look closely at one of his wall abstractions, in which the formal beauty of decay is the ostensible subject, and you'll notice this scribbled text: "I want a raise in work."

Don't think, though, that the word "new" in the title of this show means that the connections between Siskind's art and that of his painter pals at New York's Cedar Bar (along with Kline, Siskind knew Jackson Pollock, Willem de Kooning, Barnett Newman and others) are just now being uncovered. Rather, the "newness" refers to the shift in Siskind's work from documentary to abstraction, as Siskind, in the words of curator Stephen Bennett Phillips, "pushed his art in the direction of pure gesture." In other words, the relationship between Siskind's photos and ab-ex painting may not be news to us, but it was news 50 years ago.

Sander's photographs of German landscapes and trees are notable less for what they show -- mountains, streams, a distant village -- than for what they don't show. Free of overt political commentary despite having been shot during the Nazis' rise to power by an artist who was, in all likelihood, not a party sympathizer, they nevertheless avoid the kind of idealized depiction of the Fatherland that Hitler's arbiters of culture might have preferred. (The Nazis, in fact, burned the plates for one of Sander's books of portrait photography, a body of work known for its depiction of Germans not as they might have wished themselves to be seen, but as they were.) While it cannot be said that the artist's formally lovely landscapes show an ugly side of what curator Phillips calls the "national psyche," there is yet an ineffable sadness to many of the images.

This is partly due to the fact that, with the exception of a ghostly figure of a man who paused on a park bench during one long exposure, there are no people in the pictures. The absence of human beings, whose presence is nevertheless implied by footprints in the snow, barges on a far-off river and other traces, creates a mood of loneliness that is hard to shake.

Not that you would want to.

Art, as Duncan Phillips would have been the first to remind you, is meant to move the viewer.

AARON SISKIND: NEW RELATIONSHIPS IN PHOTOGRAPHY

AUGUST SANDER: PHOTOGRAPHS OF THE GERMAN LANDSCAPE

REVELATION: GEORGES ROUAULT AT WORK

All open Saturday through Sept. 5 at the Phillips Collection, 1600 21st St. NW (Metro: Dupont Circle). 202-387-2151. www.phillipscollection.org. Open Tuesday-Saturday 10 to 5; Thursdays evenings to 8:30; Sundays noon to 5. Admission $8, seniors and students $6, 18 and under free.

Public programs associated with the exhibitions include:

Thursday at 6 and 7 -- Gallery talk on "Revelation: Georges Rouault at Work."

June 24 at 6 and 7 -- Gallery talk on "Aaron Siskind: New Relationships in Photography."