As you pass by the jet-black gondola outside and through the arched entrance to the National Gallery's new Canaletto show, there is a double challenge: Forget about Venice and forget about Canaletto's reputation.

"Venice: Canaletto and His Rivals" is the first major exhibition to feature paintings by the most successful of the 18th-century vedusti, or view painters, since the Gallery's 1995 "The Glory of Venice" exhibition. And Canaletto, with his meticulously rendered architectural details and rather sedate surfaces, wasn't exactly the star of a show that reveled in dimpled flesh, swirling fabric and ecstasies both religious and erotic. The current exhibition, which was first seen at London's National Gallery, helps make a stronger case both for Canaletto and his competitors, if only by eliminating all the delicious distraction offered by sexier artists such as Giambattista Tiepolo and Sebastiano Ricci.

But is it enough? The vedusti specialized in producing what were essentially high-end souvenirs, images of Venice manufactured mainly for English gentry who wanted to bring home a memento of their time in what was already a European tourist destination. The strength of their work was its precision of detail and likeness to life, both of which can be exhausting after a half-dozen images of the iconic campanile or the Byzantine splendor of St. Mark's Basilica. The virtues of Canaletto, his instant legibility and the consistent mood of sunny quiet that pervades even his busiest paintings, are also his greatest weaknesses.

If you allow the exhibition to be about Venice, and limit your pleasure to remarking on how much Canaletto's paintings really look like Venice, then it's game over very quickly. But you if can forget the tourist's mental image of Venice, Canaletto becomes a much more interesting artist, and this exhibition offers a feast for close observation and comparison.

Forgetting Venice isn't easy. Like the pyramids of Egypt and the Taj Mahal, Venice doesn't really exist apart from pictures of Venice. When the narrator of Henry James's novella, "The Aspern Papers," takes a gondola ride through 19th-century Venice, he rather snidely refers to the city outside his boat as "the bright Venetian picture." Not a place, just a picture. The word "bright" suggests that James is almost assuredly thinking not just of any picture of Venice, but of Canaletto's Venice.

Perhaps because they were so instrumental in Canaletto's career - and that influence wasn't entirely benign - the English have a particular love-hate relation with the painter. The art critic John Ruskin deplored the painter's "servile and mindless imitation," comparing his output to the mechanical reproduction of nature offered by the newly popular daguerreotype.

A century and a half later, critics weren't much warmer about Canaletto when this show (with several notable changes) debuted in London.

Yet seen side by side with other painters plying the same trade, Canaletto's power is easier to detect. And far from being merely a photographer working with paint and brush, he felt perfectly free to change reality when it suited him. When the campanile tower proved too tall to fit into a painting, he simply downsized it. And in works such as the "Piazza San Marco, looking South and West," painted around 1731, the artist does give us views both south and west, creating an impossible perspective. In what is probably the masterpiece of the exhibition, the large-scale view of the Bacino di San Marco (or inner harbor of the city), he rendered the spars and rigging of each boat with consummate precision, yet turned the church of San Giorgio Maggiore so viewers could see its magnificent front, designed by Andrea Palladio, face on.

These liberties weren't exclusive to Canaletto, and they are present in the oldest picture in the exhibition, Gaspar van Wittel's 1697 view of the campanile and Doge's palace, with the windows of the latter "corrected" for symmetry.

Venetian painters had included Venice as a subject for centuries, but it functioned mainly as a backdrop to images that record specific religious festivals or other events.

The painter generally credited with founding the 18th-century school of Venetian view painting, Luca Carlevarijs, gives people and architecture about equal billing, reveling in the life of the city, its major festivals and pageants, its urban bustle. But while full of people, they are not always full of life. Indeed, the same lady - dressed in pink, wearing a mask and holding a fan - appears in two Carlevarijs paintings, dropped in from a pattern book. Unfortunately, these paintings have been placed far from each other, on different floors of the exhibition.

In Canaletto's work, one generally gets fewer people and a lot more liveliness. He painted his own people - it wasn't uncommon for view painters to turn this task over to specialized subcontractors - and while they have the sometimes sketchy, provisional feel one would expect when figures are incidental to architectural interest, they convey all the essentials needed to animate the canvas: A sense of motion and musculature, and an existential reason for being present, other than as mere decoration. Even the people standing around in his "Piazza San Marco, looking South and West" give a powerful sense that the day is ending, the crowds heading home, the market over.

This exhibition focuses on Canaletto exclusively in Venice. He also spent long years in London and produced some lovely architectural "fantasies" not based on any particular building. Although he began as a scene painter for the theater, he emerged with a distinctive voice as an independent artist in Venice in the 1720s, and his early paintings remain the most consistently interesting.

An early view of the Piazza San Marco looking east to St. Mark's shows the famous square in the process of being repaved, with laundry hanging from some windows and tattered awnings shading others. The church is nervously rendered and the sky darker than would become typical of his later work. Like other paintings from this early period that capture out-of-the-way places, this is Venice without the scrubbed, polished, sunny splendor that became the Canaletto cliche.

By the 1730s, Canaletto's career seemed to be largely in the hands of an Englishman named Joseph Smith, who connected the artist with clients and may have steered him toward a more bright, burnished and precise style. If one senses that the young Canaletto had a sociological appetite for the nooks and crannies of his city, the older Canaletto indulges in variety for the simple reason that he was immensely busy and had to paint something.

In all, he seems to have produced about 1,500 paintings and drawings, yet he died relatively poor in 1768. It's not clear to what extent his relationship with Smith and the English market was exploitative, and how much the consistent patronage of one particular social and ethnic group limited his artistic reach.

Judged against what other painters were doing at the same time, Canaletto comes up short. But judged against his rivals, and within the parameters of the discipline and form he helped establish, he seems like a giant. For a while, in the 1730s and early '40s, he had some serious competition from Michele Marieschi, who painted a moodier but more slapdash Venice. Marieschi's view of the Bacino, painted 1739-40, shows the skyline of Venice like a two-dimensional cutout, far in the distance.

Unfortunately, a particularly gloomy, 1737 view of the Rialto Bridge, held by the Hermitage in St. Petersburg, Russia, never made it to Washington, victim of an international squabble between the United States and Russia that has also affected the National Gallery's upcoming Gauguin show.

Marieschi died young, but Francesco Guardi, his longer-lived contemporary, picked up on some of the atmospheric volatility in Marieschi's best work; he was moving the form sharply away from the detail, clarity and poise of Canaletto. Guardi's view of the plaza outside St. Mark's during an Ascension Day festival, painted around 1777, shows the iconic church oddly framed by some temporary arcades, as if to say the old landmark was no longer central in the painter's consciousness. The exhibition ends with several Guardi paintings that are focused more on the lagoon, water and sky, and the natural surroundings of Venice, than the city itself.

By 1804, when the sculptor Canova inquired after painters focused on Venice, he was told: "There are no more view painters of repute."

It's rare for an exhibition to concentrate so cleanly and concisely on a single genus, for what is essentially the entirety of its century-long run. From the chilly stiffness of Van Wittel's view of the city, to the wispy, cotton-candy threads of Guardi, you can see a style take form, and perhaps exhaust itself.

A single painting by Pietro Bellotti, a nephew of Canaletto, shows us the lows of the form, a bland view of the Entrance to the Grand Canal, in which the materiality of the city seems to dissipate in a haze of blue and green, and the water reflects the windows of the wrong building. Works by Pietro's older brother, Bernardo Bellotto, stand up very well against his uncle's best work, with the exception of Bellotto's dogs, which look more like monkeys than canines. The strength of this show is its limited horizon, which lets the viewer focus on these kinds of details.

Without unduly stacking the deck against Canaletto's rivals, the National Gallery exhibition revives poor Canaletto's reputation at least a little. Some of the later paintings made after he returned from London, often dismissed as inferior, are stunning, including a view of St. Mark's through the darkened arch of an arcade. And at his best, as in the Rio dei Mendicanti (ca. 1723), a brooding view of one of the city's least traveled byways, Canaletto even manages to make Venice disappear. Yes, there's a canal, and there are gondolas on it. But if you can ignore both, the painting really speaks of poverty, isolation and cheap housing, like one might find in 19th-century Paris or early 20th-century New York.

This was not the Venice that British lords and ladies wanted to take home with them, if they saw it at all. But it's proof that Canaletto's vision was sharper and more questioning than it seems in the sunny souvenirs of the 1730s. Is it enough to call him a great artist? Yes, within limits, and largely ones he crafted.

Venice: Canaletto and His Rivals Venice: Canaletto and his Rivals is on display at the East Wing of the National Gallery through May 30. The exhibition is free and open Monday to Saturday 10 a.m. to 5 p.m. and Sundays 11 a.m. to 6 p.m.