Frank Stella’s magnificent new sculptures, on view at Paul Kasmin Gallery, are all flow, form, and energy. Mr. Stella is a streaky artist. Because he constantly searches out new means of art making, he occasionally slumps. A number of years ago he began producing polychrome sculptures that left me wondering if he’d gone entirely off the rails. But then, beginning with his last show – which consisted of stainless steel sculptures that were clearly in dialogue with recent developments in architecture – he once again found his winning ways.

In his current show, Mr. Stella presents work of various sizes, primarily employing stainless steel and carbon fiber and ranging from enormous floor constructions to hanging sculptures and small pieces for walls and tables. “adjoeman” (2004), a monumental structure of rhyming semicircles and spiraling tubes, topped by billowing, sail-like pieces of carbon fiber, sets the tone.

All the pieces here seem to swoop and soar. Polished or brushed planes of steel in undulating forms reminiscent of Frank Gehry’s buildings accompany a looping tube and black rectangular “sail” in “adegan” (2004), a wall sculpture. (All the titles here come from the glossary to Margaret Mead’s “Balinese Character: A Photographic Analysis”; the word “adegan,” for instance, means “showing off, decorative.”) Muted peach tones on another wall piece, “oeriaga” (2005) wink at the earlier, polychrome efforts without succumbing to a full chromatic onslaught.

Mr. Stella does, however, give in to a rush of inventiveness. Not content simply to explore the torqued planar forms afforded by computers, he adds, as a sort of counterbalance, a broken hexagon to the wavelike hanging sculpture “djaoek” (2004). Nor is he stuck in what Robert Lowell once called “our monotonous sublime.” The surging curves of the massive sculptures produce decorative, diminuendo notes in the smaller pieces.

Borne aloft by the shooting vectors of which they are composed, many of even the largest works, hanging from the wall or ceiling, seem to defy gravity. Still, none of the works hit a grave note. Mr. Stella plays weight and weightlessness, energy and stasis as nimbly as a virtuoso pianist. In this masterly performance, his compositions strike every key.

***

Enter the Marian Goodman Gallery to look at art and you will find large-format photographs of people looking at art. The German photographer Thomas Struth has been producing a sort of documentary index of museum pictures since 1989. For his new show, “Audience,” Mr. Struth captured, in large C-prints mounted on UV Plexiglas, visitors to the Galleria dell’ Accademia in Florence, without including the artworks at which they are looking. This is a slight change of approach from earlier museum pictures, which included the artworks; unfortunately, I can’t say the change marks a substantive improvement to the series.

The four biggest panels on view use the same camera placement to shoot different sets of visitors, while four smaller panels were shot from two other vantage points. In all of them, you encounter cold and frozen moments of spectatorship: groups of bag-toting tourists who pay varying degrees of attention to the art. Why we might want to pay any more than passing attention to these images is a question also left outside the frame.

Even less attention-grabbing is the video running in Goodman’s back gallery, “Read This Like Seeing It for the First Time.” A five-part video of music lessons, conducted by classical guitarist Frank Bungarten in German with English subtitles, the piece would require some five hours to watch. But, unless you’re learning classical guitar, why bother?

***

As the Struth show suggests, editing out one’s worst impulses is crucial to photographic success: Some ideas are best left as neural impulses. The Los Angeles photographer James Welling, who is showing work from three series – “Light Sources,” “Screens,” and “Flowers” – at David Zwirner Gallery, could also have benefited from some editing.

Yet, given the current predominance of off-the-cuff, vernacular color photography, I was pleased to linger over the relatively formal black-and-white Piezo Pigment Prints that make up “Light Sources,” the most intriguing of the three series. Here Mr. Welling focuses on the abstract forms discernable in a rain-streaked window, a fluorescent light fixture, a white stairwell, a cave, or a lighthouse – usually producing strong, if not groundbreaking effects.

For “Screens,” Mr. Welling dispensed with the camera, exposing metallic color paper directly to light. The results – ethereal, veil-like abstract images, in mostly yellow tones – reminded me of Wolfgang Tillmans’s abstract photos. Unlike Mr. Tillmans, however, Mr. Welling asks too much of these images, placing them in expensive-looking frames.

Still, I would have only completely edited out the “Flowers” series. Ignore the complex process Mr. Welling employed, and what you see are colorized Plumbago blossoms in red, yellow, green, blue, indigo, and violet hues on white backgrounds. This is fast-food art, the sort of easy beauty one finds in resort-town galleries.

***

The painter Ingrid Calame also hails from Los Angeles and makes abstractions from the real world, in her case by tracing graffiti and paint spills encountered on the concrete embankments of the Los Angeles River. She does each of the tracings in a different color pencil, layering them on Mylar.

Go to enough contemporary galleries and you’ll see a lot of work done on Mylar, which can yield remarkable depths, among other effects. Ms. Calame, whose works resemble topographical maps run amok, tends to prefer the shallows. Her lines and loops – in green, yellow, blue, and red – hew close to the picture plane, so that the built-up strata of unfilled silhouettes become at once dense and airy. That sense of mass without weight obtains WHAT? despite the format, though some of the pictures are as large as 11 feet by 7 feet and others are as small as the screen on my inexpensive television.

Impressive as they are, the drawings do, I think, exemplify the limits of tracing, and they suffer for it. In short, they’re too map-like: The lines are rigid and tentative the way only traced lines can be. This halting stiffness causes them to plod rather than flow, to seem reproduced rather than energetically proclaimed.

Stella until May 14 (511 W. 27th Street, between Tenth and Eleventh Avenues, 212-563-4474). Prices: The gallery declined to disclose prices.

Struth until May 7 (24 W. 57th Street, between Fifth and Madison Avenues, 212-977-7160). Prices: The galley declined to disclose prices.

Welling until May 7 (525 W. 19th Street, between Tenth Avenue and West Street, 212-727-2070). Prices: $6,300-$30,000.

Calame until April 30 (533 W. 26th Street, between Tenth and Eleventh Avenues, 212-714-9500). Prices: $3,500-$28,000.